Gypsy Sailing (tel. 505/8608-9498, justin [at] rootsengineering [dot] com, $30–40 pp) offers all-inclusive half or full-day trips, or you can charter the Pelican Eyes yacht for an all-day jaunt (tel. 505/2563-7000, www.piedrasyolas.com , $90 pp) including lunch on a deserted beach and an open bar.
The Pacific lacks the visibility of the Caribbean waters, but fish are plentiful and there’s a sunken Russian shrimp boat offshore, so it can be fun. The expert divers at San Juan's Nicaraguan owned and operated dive shop, Neptune Watersports (tel. 505/2568-2752, www.neptunenicadiving.com ), will rent you gear and take you underwater ($85 for two tanks, $350 for open-water certification) if you already have your license and are an experienced diver.