In-water access can close on cold days or for the whole winter season. Confirm refuge status the morning of the trip.
The photographs are the three vents: clear, constant spring water, a tight basin, palms on the bank. That picture is why people put Crystal River on a calendar. It is also why the refuge treats the spring as a warm-water room for Florida manatees, not as a swimming hole with a gift shop.
The boardwalk is one trip
Land access is a boardwalk and trails. You do not park on the bank and walk in. Tickets and a shuttle run through the visitor operation in Crystal River. There is no swim step, no ladder, no “just this once” from the railing. If someone tells you otherwise, they have not been on the walkway.
Boardwalk days are the right call for mixed-ability groups, for kids who should not be in a wetsuit, and for any morning when King’s Bay is a parking lot of boats. It is still wildlife. Stay on the path. Do not throw food. The animals did not come here for a selfie.
The water is a different trip
If you want to be in the spring, you come from the bay: kayak, paddleboard, or boat, launched from a public ramp in Crystal River. Hunter Springs Park and Kings Bay Park are the usual city launches. Motors stay out of the vents. Climbing the banks is not a loophole.
Manatee season at the refuge typically runs November 15 through March 31. That is when Three Sisters is most likely closed to in-water visitors. Outside that window, paddle craft are often allowed inside—still no motors, still no climbing. The morning’s ropes beat last year’s blog post. Read the manatee notes before you treat the vents as a sure swim.
King Spring is not Three Sisters
King Spring—sometimes called the Main Spring or the Keyhole—is a different basin in King’s Bay, used for snorkeling and diving next to the Banana Island sanctuary. People mix the names. Do not. A permitted tour that puts you in King Spring is not the same as a paddle into Three Sisters, and neither is a substitute for the boardwalk.
Official notes: Crystal River National Wildlife Refuge and Three Sisters Springs visitor information. If you are building a Friday-to-Sunday around this, use the weekend maps and sleep in Crystal River—see where to stay.