If you are going to camp in Dry Tortugas National Park, consider bringing or renting a kayak. Contact the Yankee Freedom about a Dry Tortugas kayak rental and to determine whether they have space to accommodate one on your trip.
Kayaks and paddleboards (as well as other recreational vehicles) in the park require a free boating permit which can be requested in person on Garden Key at the Visitor Center or the Park Headquarters Office. The visitor center is located inside the fort (just to the right through the main entrance). If you plan to travel to Loggerhead Key, this destination needs to be listed on your boat permit as it is limited to 24 people per day.
The park service lists the required equipment for any kayak trip as a life jacket, a whistle (or other sound producing device) and a flashlight (even if not planning to paddle after dark). There are also a number of “strongly recommended” items including a portable VHF radio, signalling device, first aid kit, GPS and/or compass, and several other items.
Transport of kayaks via the Yankee Freedom is limited to three per day so definitely make your reservation well in advance. The boat launch for kayaks is at the dinghy beach between the main dock and the old south coaling dock. You can contact the Yankee Freedom about kayak rental (they have a recommendation), and we also saw an online vendor advertising delivery of kayaks to the Yankee Freedom for transport.
NPS recommends that beginners should stay near Garden Key. A trip around Bush and Long Key generally takes a few hours. A kayak will allow you to get closer to the birds nesting on these islands (since you are not permitted to set foot on them). Fishing from your kayak is another reason to bring one.
Loggerhead Key is a three mile journey to the west of Garden Key across deep water which can have strong currents. It should be attempted only by experienced kayakers with appropriate equipment.
We did not bring a kayak on our trip to the Dry Tortugas in 2017 because we were only there for the day, but it would have been fun to have one to circle Garden Key.
Below is a photo of the dinghy beach where kayaks are launched (located between the docks and the south coaling dock ruins) that we took on our trip. You can see two orange kayaks sitting on the beach just above the boat.