For experienced snorkelers and divers, Cancún proper is less interesting than Isla Mujeres and doesn’t even compare to Cozumel. Cancún’s sandy seafloor simply doesn’t have the coral and rock formations that make for great underwater excursions. Where there are large reefs, as at Punta Nizúc, neglect and heavy boat traffic have killed much of the coral.

In fact, most shops simply take divers and snorkelers toward—or to—Isla Mujeres’s waters. Shops also offer diving and snorkeling trips to Cozumel and the cenotes—inland freshwater sinkholes south of Cancún, which offer superb cavern and cave diving. Both are worth the extra time and expense.

Snorkeling

For the best open-water snorkeling, book a trip with a dive shop. All those listed offer guided snorkeling trips and are invariably better than the ubiquitous “jungle trips” hawked around Cancún, even for beginners. For something different altogether, arrange a cenote snorkeling trip. The water is unbelievably clear, and swimming through and among the cave formations is otherworldly.

Scuba Diving

A number of shops offer fun dives as well as certification courses at all levels. Many hotels are affiliated with independent shops that cater exclusively to their guests; ask your concierge for more information.

See our How to Choose a Dive Shop page for more diving advice.

Solo Buceo (Dreams Cancún Hotel, Blvd. Kukulkán Km. 9.5, tel. 998/883-3979, www.solobuceo.com, 9 a.m.–4:30 p.m. daily) is a friendly shop with a strong reputation for service; in fact, most dives are led by instructors rather than dive masters. Two-tank reef dives run US$70, while two-tank Cozumel or cenote trips cost US$145, including lunch; prices include all gear except a wetsuit (US$10, recommended for cenote trips). Open-water certification classes (US$425, 3–4 days) can also be arranged. Despite its name, Solo Buceo offers more than “only diving,” including snorkeling, parasailing, deep-sea fishing, and wave runner rentals.

Scuba Cancún (Blvd. Kukulcán Km. 5, tel. 998/849-7508, www.scubacancun.com.mx, 7 a.m.–8 p.m. daily) was founded in 1980 and is still run by the same family. It offers the standard selection of dives, including one-tank (US$54), two-tank (US$68), and two-tank cavern and Cozumel dives (US$140, including lunch); all prices include equipment. Snorkel trips are offered in Cancún (US$29), Cozumel (US$95), and nearby cenotes (US$105). Trips can sometimes get crowded—ask about the size of your group before you book.

Aqua World (Blvd. Kukulcán Km. 15.2, tel. 998/848-8300, tel. in U.S./Canada 877/730-4054, www.aquaworld.com.mx, 7 a.m.–8 p.m. daily) is Cancún’s biggest, most commercialized water sports outfit, of which scuba diving is only a small part. Come here if you’re looking for activities for the whole family, divers and nondivers alike, all in one spot. Otherwise, head to smaller shops for more personal attention.

Dive Insurance

Although diving and snorkeling accidents are relatively rare, especially among beginning divers, you might consider purchasing secondary accident and/or trip insurance through the Divers Alert Network (DAN, toll-free U.S. tel. 800/446-2671, 24-hour emergency Mex. tel. 919/684-9111, accepts collect calls, www.diversalertnetwork.org), a highly regarded, international, nonprofit medical organization dedicated to the health and safety of snorkelers and recreational divers. Dive accident plans cost just US$30–75 per year, including medical and decompression coverage and limited trip and lost equipment coverage. More complete trip insurance — not a bad idea in hurricane country — and life and disability coverage are also available. To be eligible for insurance, you must be a member of DAN (US$35 per year).