Snorkeling is available if you don't mind the cool ocean water of California. Hiking is an option- you can get free hiking passes before hitting the backcountry. You can even do laundry while in town- there is a laundromat right there in town. A great place to eat and drink is the Sandtrap. Great Happy Hour! Loved the drinks, $1 tacos, and other menu items to choose from. A submarine tour is available for people wishing to view the fish without getting wet.
One of the best cities to visit. Cable cars, ice cream, sourdough bread, baseball- its got it all! You can catch a Giants game, or travel via BART to Oakland for an A's game. Just start walking and you will see stuff here that you won't see anywhere else. Alcatraz is a must-do. You can also go on tours of the bay, or nearby cities via boats around Pier 39 which also has great shopping.
If you enjoy city viewing from up high, choose from three different observation decks: Space Needle, Smith Tower, and Columbia Center. All three offer different experiences, so do all three! The Underground Tour is a must. You get to see the original Seattle (the current one was built on top of the original one). Great tour. You see the city from a unique perspective. The monorail takes you from the mall to the Space Needle and the EMP.
Old Spaghetti Factory is a nice place to stop for dinner. Don't miss the original Starbucks at Pike Place and the world's tallest Starbucks on the 40th floor of Columbia Center. The baseball stadium offers tours which is enjoyable for baseball fans. The outdoor sculpture garden is recommended for fans of art. The library is worth a stop at as well. If you start at the 10th floor, and go down, you can follow the Dewey Decimal System down the spiral walkway.
Lots to do at Canada Place which was originally the Canada Pavilion at the 1986 World's Fair. There is an IMAX theater there. Stanley Park features a statue of Lord Stanley (as in the Stanley Cup), an Aquarium, totem poles, and a beautiful area to walk around while enjoying a slice of nature right in the heart of a city.
The flowers at Butchart Gardens are a must-see. Craighdarroch Castle is an old house (very large house) with a lot of history. Tea at the Empress is the ultimate afternoon tea experience.