Cruise ship arrived in Philipsburg on the dutch side. Downtown is a 10 min walk to the left of the port. It's a wonderful nice little down full of stores, a beach right downtown with lines of stores were the beach ends. Very pretty combination of ocean with green hills.
A 2 USD per person ride on public bus will take you to Marigot, the French capital. There's not much to see other than a few restaurants and a market but still is interesting to see how different both towns are. Incredible to see how to different cultures can peacefully coexist is such a small piece of land.
Downtown Basseterre is busy and except for the Cathedral there's not much to see. Head to UNESCO World Heritage Site Brimstone Hill Fortress. It's a must see in Basseterre. It's a 30 min drive from the port and the cab cost us 50 USD (apparently it's the government set rate because we asked around and everybody gave us the same price). The exhibitions in the fort are not all that impressive but the view and the architecture of the place are what matters. It's worth the trip.
We arrived on a Saturday when the market was in full swing and it covered several blocks of the capital. We didn't take a shore excursion but it might be worth it to go see more of the island because in Kinsgstown there's nothing to see. Not even the two churches are worth it and they're a long walk from the port especially when you have to fight your way through the busy market.
The Parliament in Barbados is a UNESCO World Heritage Site. Take a 2 USD per person shuttle there to see the building and once there cross the bridge and walk left and you'll find a wonderful beach right there close to the city with pink beaches and sea stars in the bottom of the crystal clear water. Barbados is a must for the beach. If you want to spend more they'll take you to better beaches but this one was so beautiful that we didn't need to go elsewhere and you can walk right back to the ship if you want.
Martinique is very French indeed. In Fort-de-France you will find Galleries LaFayette and pharmacies carrying the same beauty products as those in France do. Other than the Schoelcher Library and Josephine's beheaded statue in front of it there's not much to see in the city.
The biggest issue is the ship is docked very far from the entrance of the port and especially in hot weather it's terrible. Plus adding the walk to downtown it gets really uncomfortable. However, the cab costs 8 euros to downtown or two per person if you share. It's highly recommended as they're waiting very close to the ship and they save you a really long walk in the scorching sun.
Another pointer is that the port provided free wi-fi but if you don't need it badly don't bother. It has too many security protections and you have to put in a password to get to another password to put in an address, etc. etc. It's really a hassle and the most complicated wi-fi I've seen in the world.
The cruise ships arrive at Frederiksted but in the port entrance there are very well organized shuttles waiting to take you on the 40 min drive to Christiansted for 16 USD (there's no negotiating needed as this is the flat rate). Downtown Christiansted is a well preserved dutch town with the Government House and Fort as its highlights. It's pretty but small to navigate so it doesn't take much time.
Frederiksted is less well preserved so it's not recommended to spend much time here. Immediately to the left of the port entrance you can find the Frederiksted fort and a beach. It must be the closest beach to the ship I've seen in the Caribbean. It's very convenient if you want to go to the beach hassle free.
Half Moon Cay is the cruise line private island and no wonder they chose this location because it's gorgeous! You have to get a tender ashore because the water gets really shallow near the beach which allows you to get really far into the sea and still touch ground. The sea is very calm and looks more like a pool with wonderful hues of blue. The water is crystal clear and if you have goggles it's easy to spot fish. It's really the picture of paradise.