Cancun · Mexico
A Cozumel day trip from Cancun means waking up early for a 45-minute ferry ride across sometimes choppy water. Once there you’ll find a busy port town surrounded by decent snorkel and dive sites, a few nice beaches, and rental scooters or taxis to get around. The reef is noticeably healthier than what you’ll see on the mainland, but the main tourist areas get packed with cruise-ship passengers by mid-morning. Expect a full day of travel and logistics; you’ll be back in Cancun after dark.
Best time is December through early April when seas are calmer and visibility is good. July–October can be hot, humid, and more likely to have rough crossings or afternoon rain. Expect to pay around $120–$220 per person depending on whether you just take the ferry and wander, or add a snorkel tour, beach club, or guided excursion. Food and drinks on the island add another $30–$60 easily.
Honest tip: rent a scooter and head to the east side of the island for quieter beaches and better snorkeling; skip the overpriced “all-inclusive” beach clubs right off the ferry pier. Bring reef-safe sunscreen, cash for small vendors, and don’t over-schedule the day. If you mainly want great snorkeling and don’t mind the boat ride, it’s solid. If you’re short on time or get seasick easily, you’re probably better off staying on the mainland.