Isla Zacatillo is one of the most accessible island stops from La Unión, a fishing community set in the Gulf of Fonseca east of the port. It is small, quiet, and best approached with the right expectations: simple seafood, views across the gulf, and a glimpse of island life rather than organised attractions.
Boats can usually be arranged from La Unión's waterfront, often as part of a wider gulf trip. Ask about return times before you go, and do not assume services run late. The island is most appealing in the morning, before the heat flattens everything.