Soak up some sun and relax on the beach
Kayaking
Jet Skiing
Boating
Fishing
There are a ton of trails in Big Bear. These are just a few:
Castle Rock 2.4 mi round trip (intermediate/difficult)
Pine Knot Trail 6 mi round trip (intermediate)
The Woodland Interpretive Trail 1.5 mi loop (easy)
*Just remember that you are hiking at a higher elevation. Drink lots of water!