Yes, you can do the Key West Express as a day trip, but it results in a very long day with relatively limited time on the island. The ferry typically departs from Fort Myers Beach or Marco Island at around 8:00 AM or 8:30 AM. The journey across the Gulf of Mexico takes approximately 3.5 hours each way, depending on the sea conditions. This means you arrive in Key West around noon and must be back at the docks for the return boarding at approximately 5:00 PM or 6:00 PM. This schedule gives you about 5 to 6 hours to explore the "Conch Republic." While this is enough time to have a nice lunch on Duval Street, visit the Ernest Hemingway Home, or see the Southernmost Point buoy, you will miss the world-famous Sunset Celebration at Mallory Square, as the ferry departs before the sun goes down. In 2026, many travelers find that a day trip is a great way to "scout" the island, but those who want to experience the legendary nightlife and relaxed pace of the Florida Keys often choose to stay at least one night. If you do a day trip, it is vital to check the weather forecast, as rough seas can make the 7-hour round-trip journey quite uncomfortable for those prone to motion sickness.