Grand Lake St. Marys is the largest inland lake in Ohio by area, covering about 13,500 acres in Mercer and Auglaize counties.
We rent MasterCraft wakesurf boats, Sea-Doo jet skis and water toys on Grand Lake St. Marys, and everything is ready for you at the lake. Add a captained charter with lessons for every level.
It's wide and shallow, averaging only 5 to 7 feet deep, with Celina on the west end, St. Marys on the east and Grand Lake St. Marys State Park facilities all around the shore.
Boat, jet ski and water toy rentals at Grand Lake St. Marys
Your rentals are waiting for you at Grand Lake St. Marys, so there's no truck, no trailer and no towing to worry about.
- Wakesurf and ski boat rentals – MasterCraft boats seating 12 to 18, set up for a full day of surfing, skiing and tubing on Grand Lake St. Marys.
- Sea-Doo rentals – rent a single jet ski or several for your group's day on Grand Lake St. Marys.
- Captained charters – sit back and enjoy Grand Lake St. Marys while our captain drives, or learn to wakesurf with one-on-one coaching.
- Water toys – tubes, lily pads, water trampolines, paddle boards and more to keep the whole group busy.
Book Now or call or text 1-888-594-6610 – we answer 7 a.m.–10 p.m. every day.
Grand Lake St. Marys at a glance
| Location | Celina and St. Marys |
|---|---|
| Size | About 13,500 acres |
| Avg depth | About 5 to 7 feet |
| Rank | Largest inland lake in Ohio |
| Counties | Mercer and Auglaize |
| Park | Grand Lake St. Marys State Park |
Best things to do on Grand Lake St. Marys
- Water skiing and tubing – open water on the main lake.
- Jet skiing – open water and quiet coves.
- Sunset cruises – wide-open views across the lake.
- Fishing – crappie, perch and catfish.
Where to launch at Grand Lake St. Marys
- State park ramps – public launches around the lake.
The shallow lake gets choppy in the wind, so mornings are smoothest. Your rental from us is ready at the lake.
Tips for a great day on Grand Lake St. Marys
- Mornings are calmest for surfing.
- Ohio requires an observer besides the driver when towing.
- Jet skis can't run between sunset and sunrise in Ohio.
Ohio boating rules to know
- Every boat needs a wearable life jacket for each person on board. Children under 10 must wear one on boats under 18 feet, and everyone on a jet ski or being towed must wear one.
- Towing a skier, wakeboarder or tuber requires an observer besides the driver, and the person being towed must wear a life jacket. Towing isn't allowed between sunset and sunrise.
- Jet skis can't be operated between sunset and sunrise, and the engine cut-off lanyard must be attached to the driver.
- Keep to no-wake speed in posted no-wake zones and shore zones, and slow down near docks, marinas and swimmers.
Map of Grand Lake St. Marys
Grand Lake St. Marys rental & boating FAQ
What can I rent at Grand Lake St. Marys?
Wakesurf boats, Sea-Doo jet skis, water toys, and private charters with a driver-instructor — everything for a full day on the water.
Do I need a truck to tow the boat?
No. Your boat or jet skis are ready for you at Grand Lake St. Marys, so there's no towing.
Where is Grand Lake St. Marys?
In western Ohio between Celina and St. Marys, in Mercer and Auglaize counties.
Can you jet ski on Grand Lake St. Marys?
Yes. Jet skiing, waterskiing, wakeboarding and wakesurfing are all popular on Grand Lake St. Marys.
How big is Grand Lake St. Marys?
About 13,500 acres, the largest inland lake in Ohio by area.
Is Grand Lake St. Marys deep?
No. It averages only about 5 to 7 feet deep, so it gets choppy quickly in the wind.