A PWC (personal watercraft / jetski) is the fastest and most agile option for circumnavigating Manhattan. These machines hit 60+ mph easily, handle tight turns, and can punch through rough water. In ideal conditions—slack tide, early morning, minimal traffic—a rider could theoretically lap the 28.5-mile loop in under 45 minutes.
But here's the catch: Manhattan's waters are dense with no-wake zones. Battery Park, the entire southern tip, Roosevelt Island, and most of the Harlem River are restricted. The East River has ferry channels. And Hell Gate? It will try to kill you regardless of what you're riding.
For a PWC, bridge clearances are a non-issue. The real enemy is regulation, enforcement, and the unpredictable hydraulics where three rivers meet.