The E-M5 II will also do 'electronic zoom'. Not jump, zoom. The 1fish/3fish setting on page 67 jumps between 12mm and 50mm. On page 66 of the manual, set camera to assign function to each arrow. On page 68, set a button function to Electronic Zoom (for example Up Arrow). When using the camera, press to assigned function button to activate Electronic Zoom. Then use the arrow keys to zoom in or out. In the upper right corner of the display you will see the setting of the zoom: 12mm, 20mm, 27mm, 45mm, whatever. See Item 12 on page 19.
I just received a 39 scope cap. It is NOT the correct size. The outside dimension of my 45 VF, with the rubber eye piece, is 53mm. It looks like size 33 (30330) is more appropriate. Shame on me for not measuring first.
Underwater mode (1-fish/3-fish) will 'jump' between 12 mm and 50 mm, but it will also change the aperture and speed to some predetermined settings (not configurable). Using the mode switch to switch from, and back to M will return the settings to the ones you have previously set and leave the lens in the zoom in or out position. Not very user friendly. Better, and easier, way is to set up 'electric zoom'. Hit the left arrow to activate. The use up and down arrows to zoom in or out. Upper right corner of the display will show zoom setting. Aperture and speed will not be affected.