Miami has no single tour harbour. Four separate marinas send boats onto Biscayne Bay, the two downtown ones sit a mile apart on the same boulevard, and one of them answers to two names.
Miamarina at Bayside, 401 Biscayne Boulevard, is the city-owned marina inside Bayside Marketplace and the one most people mean by "the Miami boat tour": 125 slips at the west end of Government Cut, with the sightseeing operators loading from the promenade beside the shops. It is also the easiest pier to reach without a car — the free Metromover's College/Bayside station is one block west.
1635 North Bayshore Drive, a mile north towards the Venetian Causeway, takes most of the island and sandbar trips. The signs and the dock staff say Venetian Marina & Yacht Club, the name Integra Marinas gave it; half the listings still say Sea Isle Marina, which is what it was called for decades. Same water, same gate; check-in is at Pier 1, forty-five minutes ahead.
Miami Beach Marina, 300 Alton Road, sits across the causeway at the southern tip of South Beach: 400 slips, small charters and dive boats, walking distance from the Art Deco district. Parking is the city's pay-to-park scheme, not the marina's, and it fills by midday.
Haulover, sixteen kilometres north, is a Miami-Dade County park holding Bill Bird Marina and the Haulover Marine Center. No tour on this page leaves from it, but its ramp is where you go if you rent rather than book, and the sandbar off it is the one a captain may mean by "the sandbar".