Yes, you can absolutely boat from Detroit to Cedar Point (Sandusky, Ohio) across western Lake Erie. The straight-line distance is roughly 60 nautical miles—a day trip for a capable powerboat, an overnight for a sailor. Here are the practical options:
Not a direct Detroit departure, but the most popular public option. Drive ~30 minutes south to the Luna Pier, MI terminal (or walk on from Toledo). The ferry crosses to Put-in-Bay (South Bass Island) in ~2 hours, then a short drive to Cedar Point. Seasonal (April–November). Reservations recommended for vehicles.
Direct crossing: 3–5 hours depending on vessel speed and lake conditions. Depart from Detroit River marinas (e.g., Detroit Yacht Club, Wyandotte, Gibraltar), follow the shipping channel south into Lake Erie, then southwest to Sandusky Bay. Critical: Check marine forecasts—Lake Erie's shallow depth (avg. 62 ft) makes it notoriously choppy in wind. File a float plan. Carry charts (NOAA 14820, 14830) and VHF radio.
Several Lake Erie charter captains offer Cedar Point runs, often combining fishing (walleye, perch, smallmouth) with the crossing. A good choice if you lack offshore experience or a suitable boat.
For boaters, the Detroit–Cedar Point run is a classic Great Lakes cruise—just respect the lake's temperament.