Start with which side of the island you are on. The Atlantic, in front of Ocean Drive and Lummus Park, is a lifeguarded swimming beach: the watersports you will see there are the concessions operating off individual hotel stretches, and they work inside a permitted footprint rather than roaring up and down the shoreline. The bay behind the island is where the engines live. Jet skis, parasail boats, charter fleets and paddle outfits all launch from the western side, and the walk from Ocean Drive to that water is about ten minutes across three streets.
That single fact reorganises the day. If somebody on the sand offers to put you on a jet ski, ask where the machine is and how you get to it, because the answer is usually a van ride to a bay dock. Booking directly at a bay-side operator, or through a listing with a named departure point, removes a step that has a habit of costing an hour.
The two clusters worth knowing are the marina at the bottom of the island on Alton Road, where most of the jet ski and parasail fleets sit alongside the charter boats, and the quieter basins around Sunset Harbour and Maurice Gibb Memorial Park at the northern end of the neighbourhood, which is where the kayak and paddleboard operators are because the water there is flat, shallow and protected.
The water itself is not the open ocean. Biscayne Bay between here and the mainland is a shallow, warm, enclosed body with a hard sand bottom, marked channels, dredged spoil islands and a lot of boat traffic. It is flat at seven in the morning, corrugated by eleven when the sea breeze fills in, and busy enough at weekends that the safest hour is the earliest one. Large parts of it are posted manatee protection zones where speed is restricted to idle or slow, and those are enforced by marine patrol rather than by goodwill.
Florida has real rules about who may ride. Anyone born on or after 1 January 1988 needs a Boating Safety Education Identification Card to operate a personal watercraft, which for most visitors means sitting a short online course; rental companies generally require the person signing to be at least eighteen. Nobody rides after dark: operating a personal watercraft between sunset and sunrise is prohibited statewide.
And then there is the contract, which is the part of this transaction that generates the arguments. The section below on deposits and damage claims is the most useful thing on this page.