The regularly scheduled ferries leave from Marigot on the French side of St Martin. There are several companies, meaning that ferry service is essentially hourly during daylight hours. Link Ferries is just one operator, but they have a website. The crossing takes only about twenty minutes, and should cost about $15 (including departure tax) one-way. Don't buy a round-trip ticket as this will limit your return options.

Ferries are organized from the Dutch side of St Maarten when there is a concert or some special event on Anguilla. They do not run regularly from the Dutch side, but boats can be easily chartered.