If ever you needed an excuse to take a cruise, experiencing the Panama Canal -- one of the most important innovations in history -- is a darn good one. After all, the canal was one of the largest and most difficult engineering projects of all time; it took years to build and forever changed the maritime landscape, making it possible for vessels -- and, eventually, modern-day cruise ships -- to transit from the Pacific Ocean to the Caribbean Sea without having to circle South America.

I was fascinated with the logistics -- how it was built and how it works. But, beyond the actual man-made marvel, Panama Canal cruises offer unique opportunities to visit ports in Central America and, depending on the itinerary, surrounding regions like the Mexican Riviera or the Caribbean.

And, while the Panama Canal is principally known for attracting senior travelers because of the longer length of most itineraries and the historical nature of the subject matter, there is plenty to appeal to younger cruisers like me (late 20's). Colorful Curacao and lush Costa Rica, for example, offer a plethora of active excursions and richly varied environmental experiences for nature lovers.

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Different Roads, Same Destination
Because the Panama Canal was constructed to offer ships easy access between the Atlantic and Pacific Oceans, the natural itinerary is one that crosses through the canal, hitting ports in the Mexican Riviera, Central America and Caribbean on a route from California to Florida or San Juan. For awhile, this standard route -- which takes about two weeks -- was pretty much all that was offered.

This type of itinerary, considered a full transit, is still the most popular; you spend a day on the canal as the ship crosses from ocean to ocean, via the entire series of locks. But, because the actual canal transit takes a full day, passengers generally cannot get off the ship to do tours in the middle.

Partial transits are different. These cruises go only partway through and work like this: The ship enters the canal and transits one or two sets of locks on either the Pacific or Caribbean side; then, passengers are able debark for day trips -- such as tours through additional locks on smaller ferries or visits to Panamanian rainforests or Indian villages -- that full transit passengers wouldn't ordinarily experience. The ship then exits the canal the way it came in, allowing the cruise to end just where it began (generally Los Angeles or San Diego in the west and Ft. Lauderdale or San Juan in the east).

This is a good option if, like me, you can't commit to a 14-day full-transit cruise or if you want to avoid expensive, one-way or open-jaw airfare between different cities. Among the cruise lines offering partial transits are Holland America, Princess, Royal Caribbean, Celebrity and MSC Cruises.

I opted for a partial transit itinerary, as I simply cannot escape from my job, home and other responsibilities for more than those 10 days. On Zuiderdam, I particularly liked that the itinerary -- calling on Aruba, Curacao, Half Moon Cay (Holland America's gorgeous private island) and Puerto Limon, Costa Rica -- would offer opportunities to both relax on the beach and do some more active exploration.

Oh, and there is a third option: Do a full transit -- twice -- which means you still sail roundtrip from the same departure city without the concern of open-jaw airfare. The caveat, of course, is that these cruises are nearly a month long. (For example, there are two 28-night options onboard Holland America's Statendam: Go from Pacific to Caribbean and back to Pacific, roundtrip San Diego, or go from Caribbean to Pacific and back to Caribbean, roundtrip Ft. Lauderdale.)

A Brief History
Though the Panama Canal was successfully built by the U.S. between 1904 and 1914, the concept was born centuries earlier. In the 1500's, in an attempt to simplify the process of transporting goods from Spain to Ecuador and Peru, Spaniards drew up the very first plan to build a canal. But nothing came of it, due to European politics and simple lack of technology.

The first serious contenders were the French -- who actually created a company in the late 1800's and began work on the project -- but their attempts at construction failed, and the contract passed over to the U.S. (partly because they underestimated the difficulty of the tasks at hand and partly because they continually lost crew to inexplicable illnesses, later determined to be yellow fever and malaria). More than 20,000 workers died while working on the project.

After the canal was completed, the U.S. initially had control over a five-mile-wide area on either side of the canal. It was known as the Canal Zone, which created territorial tensions between Americans and Panamanians throughout the early to mid-1900's. In 1977, a treaty was signed that established the canal as a neutral international waterway, and by 1999, the entirety of the Canal Zone was returned to Panama.

Going All the Way
Even though the trip was a partial transit, covering only the eastern Gatun Locks, I'd already learned from Cruise Critic's message boards that I could theoretically see the entire canal, via shore excursions that are designed to give those who aren't going through all three locks on their cruise ship the chance to do so on a smaller vessel.

The best way to do that is to take the Canal Experience tour, offered by most cruise lines from Gatun Lake, where the ship anchors after its Gatun Locks transit. After a bus ride (about two hours) to Gamboa, in the heart of the Panamanian rainforest, we boarded a ferry that transited the remaining two locks -- Pedro Miguel and Miraflores -- so that we ended up in the Pacific Ocean. We met back up with the ship in Colon after another two-hour bus ride.

It was a long day, but it was worth the bragging rights: Why see just one set of locks when you can see all three? The itinerary, coupled with the tour, allowed me to have a more intimate canal experience. From the ferry, I was able to actually reach out over the railing and touch one of the wet (and, yes, somewhat slimy) chamber walls -- and spot lazy alligators sunning alongside the canal route.

However, if going through Gatun -- the biggest and most dramatic part of the day, no question -- is sufficient (and it may well be if you aren't a huge history buff), consider doing something a bit different with the rest of your day so that you can see more of Panama than just the locks. One option that piqued my interest was a visit to the village of the Embera Indians, one of two tribes who call Panama home. This is not a tour where the tourists and the locals are all bused to a staged location; visitors reach the remote area via canoe and experience native songs and dance performances.

Getting the Most of the Transit
Whether partial or full, the transit, for most passengers, is obviously the highlight of any Panama Canal itinerary, and you'll want to make the most of what might be a once-in-a-lifetime experience. Here are three tips, based on our trip:

1. Get up early. Zuiderdam brought aboard a local pilot at around 5:30 a.m., but passengers had started assembling on the bow well before then -- as early as 4 a.m. in the case of a few enterprising Cruise Critic members, who made it to the very front (a la Leonardo DiCaprio in "Titanic"). Truthfully, you don't have to rise quite that early -- "crew only" areas, completely forward, were also accessible, and, on this ship, so was the top-most Crow's Nest lounge with floor-to-ceiling windows. But, the sooner you can pull yourself out of bed, the better the spot you'll snag.

2. Get your sunscreen on! Despite the early start, you'll want to be prepared for the Panama sun. I really didn't anticipate needing sunscreen or a hat, but as soon as that sun came up, it was surprisingly hot. Crewmembers were on deck to hand out chilled towels -- as well as water, juice and Panama rolls (Danish-like pastries with sweet fruit filling in the center) so that passengers could enjoy breakfast al fresco, while awaiting the transit.

3. Get out of your cabin. Here's one situation where a balcony cabin offers a unique perspective, but it isn't really a necessity (unlike on an itinerary like Alaska or Hawaii, where you're guaranteed gorgeous scenery on either side of your ship). Zuiderdam just barely squeaked into the canal, with only two feet to spare on either side! Looking down over the railing of the balcony certainly gave me a better appreciation for just how tight that squeeze is, but being up on the bow is really the only way to appreciate the full scope of the process -- I watched the chamber ahead of us fill with water, while still having the peripheral vision to spot a toothy croc on the shoreline.

A Look at the Locks
So how does the canal work? Basically, the 48-mile route consists of three sets of locks amid several artificial lakes and channels. The Gatun Locks, at the eastern entrance of the Canal (the only locks Zuiderdam traversed on this partial-transit itinerary), raise ships some 85 feet above sea level to Gatun Lake, via three chambers, and there are two lanes to either accommodate two side-by-side ships or two-way traffic.

Once the ship sails into the first chamber, a heavy gate closes behind it, and water is transferred into the chamber slowly, by gravity, until the level equalizes with the next chamber. Eight locomotives that ride on rails alongside the locks tie up to the ship (four or six for smaller ships; eight is the max) but only do so to help it stay steady -- the ship moves under its own power. The forward gate then opens, allowing the ship to move into the second chamber, where the process repeats. On the other end, the Pedro Miguel and Miraflores Locks carry out this process in reverse, lowering ships back down to sea level so that they may sail out into the Pacific Ocean.

The filling (and emptying) of the chambers is gradual, so you won't feel the movement. However, you can certainly see it. I popped into the onboard theater, which I knew had portholes, to watch the lower decks of the ship dip deeper down. Eventually, all you could see through the window were the damp, brown walls of the chamber!

Beyond the Canal
In the west, Mexican Rivera ports like Acapulco and Cabo San Lucas are common stops, and cruises often depart from cities in California. For example, Princess offers a 19-night Pacific Panama Canal itinerary aboard Coral Princess, roundtrip from Los Angeles, that calls on those two ports, as well as Costa Rica's Puntarenas, Ixtapa/Zihuatanejo, Puerto Vallarta, Puerto Corinto in Nicaragua and Puerto Quetzal in Guatemala.

In the east, Panama Canal cruises feature ports in Central America and the more exotic reaches of the Caribbean. On our cruise -- which also included Aruba, Curacao (where we went swimming with dolphins) and Half Moon Cay (Holland America's private island) -- Puerto Limon in Costa Rica was the highlight. This Central America port is what my brother (my travel companion and a first-time cruiser) envisioned the Caribbean would be -- more lush greenery, fewer jewelry stores. It's definitely a port where you have to get out and do something -- whether it's active, like our kayaking trip through a quiet lagoon, or simply touring the wildlife-filled rainforests that blanket the island, much of which is a nature reserve. Other shore tour options include zipping among the treetops on a series of pulleys and cables and getting your heart rate up on white water rafting trips. (You might even spot a crocodile or two.)

Satisfying on-shore experiences abound in other ports, too. A tour of Cartagena, another Central American port, visits several sites: the Fort of San Filipe de Barajas, the Naval Museum, the Church of San Pedro Claver and the Inquisition Palace. On the Mexican Riviera side, you can also try a zip line (in Puerta Vallarta), or explore other eco-pursuits, from whale watching in Acapulco to deep-sea fishing in Ixtapa. In the Caribbean, tap into your inner shutterbug at the Butterfly Farm in Aruba, or simply relax on a quiet beach.

What to Watch Out For
It's important to use common sense and good judgment wherever you go, no matter the crime rate. However, there are places where extra diligence is wise, and the ports on the Panama Canal and Central America circuit are among them. Though you can walk into Puerto Limon easily from where the ship is docked, it is a good idea to do an organized tour there -- either through your cruise line or a private operator. The guide on my shore-sponsored kayaking tour was quick to tell us that, if we did go into town, we should keep a close watch on our wallets and other belongings.

Pushers of certain recreational drugs are also fairly prevalent on some of the islands visited on these itineraries, though our story is more funny than frightening. During the trip, my brother and I were approached nine times (seven in Aruba, two in Curacao) to purchase marijuana. My brother -- a young, goateed male -- certainly stood out amid a much older passenger base. After the first few times, we made a game of it and started to guess ahead of time who we thought would attempt to sell to us: "Want to buy some herb?" "Want to buy some good smoke?" "Want to buy some marijuana?"

While getting ready to catch the ferry back in Curacao we spotted an elderly woman with a grandmotherly smile and silvery hair. She looked straight at us and said, "Want to buy…" My brother and I glanced at one another incredulously.

She finished, "...a poncho?" Turns out, she was talking to her husband, who happened to be standing right behind us. We shared a good laugh (and a sigh of relief)!

Did You Know?
You can watch ships' transits in real time by visiting www.pancanal.com

Sailing through the canal -- rather than circling Cape Horn -- is almost 8,000 nautical miles shorter, which allows seafarers to save money, time and fuel, even with the cost of transit factored in.

Speaking of costs, there is a toll to pay. Most vessels pay a toll that's calculated per net ton. A ship the size of Zuiderdam pays more than $300,000 for the privilege of passage. The cheapest? Writer Richard Halliburton swam the canal in the late 20's and paid just a couple of cents.

Ships passing through the canal from the Caribbean Sea to the Pacific Ocean actually move from the northwest to the southeast, due to the orientation of the Isthmus of Panama.

A growing number of vessels, both cargo and cruise, are too large to fit through the canal. (You'll often hear them referred to as post-Panamax.) However, an expansion project that will widen the canal so that it is large enough to accommodate even the mammoth Oasis of the Seas (currently on order) began in 2007. The project is expected to be completed in 2014.