Honduras' mountains, Maya ruins, rainforests, and abundant reefs draw eco-adventurers seeking a good-value vacation amid splendid natural settings. The three biggest of the Bay Islands—Roatán, Guanaja, and Utila—reward travelers with some of the Caribbean's best snorkeling and diving. For families, Roatán, the most developed of the Bay Islands and home to the Roatán Institute for Marine Sciences (located at family-friendly Anthony's Key Resort), is the best bet for exploring Honduras' spectacular underwater wonders. The Institute, open to day guests, has a small museum with exhibits on reptiles and reef life, but the dolphins are the highlight. Watch them perform at the dolphin show or get up close to these loveable critters by swimming or diving with them (book ahead).

A top-rated dive destination, Roatán's calm, clear water works perfectly for families who want to learn how to scuba (do the classroom work at home so you can maximize your time exploring the reef). A short swim from shore or a 10- to 20-minute boat ride from the West End or from Anthony's Key Resort in the Sandy Bay area will take you to dive sites. So, forget about enduring stomach-churning cruises.

Two of the dive companies operating out of the West End include Sueño del Mar and West End Divers, both of which also offer snorkeling tours. Some companies welcome snorkelers on dive boats and others don't, so check ahead before reserving a spot. Also, large cruise ships dock in Roatán, where they make reservations for their passengers with nearby outfitters, so always reserve excursions in advance.

With visibility more than 100 feet in some places, many dive sites work well for snorkelers too. The Blue Channel, reachable from the shore near the Sueño del Mar Dive Center, delights mask and fin enthusiasts with its puffer fish, moray eels, schools of tangs and grunts, as well as big groupers. Herbie's Fantasy, located off Key Point, attracts novice snorkelers and divers who want to stay relatively close to shore. Vibrantly colored sea fans and sponges along with flounders, stingrays, and conchs reward the curious. Intermediate sites, great for night explorations when the corals turn pink, purple, yellow, and other vivid colors, include Valley of the Kings, known for its sponges, black corals, and sea fans and also Peter's Place, best for divers, not snorkelers. Peter's Place showcases schools of parrot fish, anglefish, and blue tangs and at night you're likely to see sponges, spider crabs, eels, and even octopi.

In general, Roatán's rocky southern shore has few beaches. The best sands stretch along the island's western and northern shores. West Bay, also known as Tabyana Beach, offers a good-sized swath of palm tree-lined sands, a nice retreat when cruise ships aren't around.

Tip: Alas, Roatán's beaches can be rife with sand flies, tiny insects whose bites leave red itchy welts. Use insect repellant and bring long-sleeved shirts and pants to wear in case the flies are biting.