Motorboat Mayhem is not a named location in Fortnite, so you won't see it on the map. It's a landmark, so there's no actual marker or waypoint to take you there. You can find the Motorboat Mayhem next to the big poop that leads to the Hydro 16 site, right next to Lazy Lake. We have marked the exact location on the map below.
Speedboat Mayhem is an area that can take on some challenges, and it's a solid place to land at the start of a round. Unsurprisingly, there are plenty of speedboats in the area, as well as a Choppa on the island in the middle of Lazy Lake. The area is also filled with ammo boxes, loot boxes, and even loot sharks. Fishing is plentiful here, so you can also stock up on weapons and supplies this way if you want.
You can also run time trials here, which is one of the Season 3 Week 4 challenges. against the watch. A timer will start counting down, and when it hits zero, you can move forward, in the rings that will appear. Follow the rings around, making sure to cross the new ones that appear as you go through them. There will be additional rings on the course, we guess in an attempt to confuse you, be sure to aim for the most recent ring each time. You'll eventually be taken back to the start line, and the time trial will end when you cross it.
Once you're done in the area, you can choose to head to Lazy Lake, Misty Meadows, or hop in the Choppa and go anywhere on the map, which makes it a pretty good starting point to n' any game.
