XTC is the one-stop spot for all your travel needs. It offers dive and snorkel trips to the wondrous barrier reef offshore and to Banco Chinchorro. It also rents out diving equipment, provides PADI open-water certification (US$600), and operates fishing and bird-watching tours (US$75). Kayaks, free for guests, can be rented for a half/full day for US$40/60.
Additionally, XTC rents nice rooms (US$115 to US$130) and a larger apartment (US$250), and has a good restaurant-bar. It's 300m north of town.