We were there just a couple weeks ago. We have taken GB Express near the airport and also have done a day trip out of the marina in SXM but we prefer to take the public ferry. Public ferry is $20 a person each way. There is a $5/ person departure tax from SXM, not sure what the tax is to leave Anguilla. We paid $23/person but were staying overnight which is more. There are plenty of taxi drivers who will take you to the beach of your choice. They will also pick you up at a specified time so you can make the ferry back to St.Martin. We took a boat trip one year but were very disappointed. We just wanted to spend our day on Anguilla, not on a boat cruising around. Wish I could remember the name of the boat. Our only
time all day was for lunch for about an hour, no swimming etc on Anguilla. If you do decide on a boat tour, get one that will take you to Shoal Bay East! There is one that goes there and lunch is served at Tropical Sunset. We have seen and talked to the folks many times and everyone seems happy with the trip!