Olympus also made some minor upgrades to the E-M1 and E-M5 II, adding an “underwater mode”.
“Addition of “Underwater” Picture Mode with control for white balance, exposure and flash compensation, aperture and shutter speed. We recommend setting Custom Menu G/ + WB to OFF.”
While the E-M1 and E-M5 II are weather sealed, they are not waterproof so don’t take them underwater without a waterproof housing.
The E-M1 also gains the E-M5 II “Live View Boost II” ability as well.
Olympus E-M5 II Firmware 1.2: Download Link
Olympus E-M1 Firmware 3.1: Download Link