If you book anything that floats in South Beach — a jet ski hour, a sightseeing speedboat, a sunset sail, a fishing charter, a private catamaran — there is a strong chance you will be told to arrive at 300 Alton Road. The Miami Beach Marina occupies the south-western corner of the island at South of Fifth, and it holds around four hundred slips taking vessels up to roughly two hundred and fifty feet.
The reason it dominates is geography rather than marketing. The marina sits on Government Cut, the shipping channel dredged in 1905 to give ocean-going vessels a direct route into the Port of Miami. From a berth here you turn left and you are in the Atlantic within minutes. Every other marina on this side of the bay requires a slow, no-wake crawl through Biscayne Bay before anything opens up. On a two-hour charter, that difference is most of your trip.
The second consequence is the view from the dock. Everything entering or leaving PortMiami passes the end of this basin: cruise ships at close range, container vessels, pilot boats, the occasional naval visit. You can stand on the public walkway with a coffee and watch a ship the size of a city block go past, which costs nothing.
What the marina is not is an attraction with a gate. It is a working facility: fuel dock, ships' store, charter offices, a long-standing waterfront restaurant in Monty's, and a lot of people carrying ice. Visitors are welcome on the walkways. Nobody is putting on a show.
It also has an uncertain future, and that is worth knowing. In 2026 the operators filed plans to redevelop part of the site, including a roughly fourteen-storey office building at 344 Alton Road alongside parking, retail and marina improvements. Because the marina sits on public land, the proposal needs both City Commission approval and a city-wide referendum, and it is being actively fought by South of Fifth residents. What is here now may not be here in five years.