Olympus is known for having some over the top weather sealing, but fully submerging a camera with a lens is something that shouldn’t happen often. The above youtuber decided to push his Olympus OM-D E-M1X beyond what any reasonable photographer can expect from their camera and the E-M1X handled the testing flawlessly. I highly recommend you not try this at home, but if you want to see someone try it with there camera fast forward to around the 7 minute mark above.
Olympus OM-D E-M1X: B&H Photo / Amazon / Adorama