Best reply so far.
I hate to be the Olympus shill, but for $500 you can get the E-PM1 package (camera, 14-42 lens, housing, zoom gear) and add $500 for the Zen 9-18 (14-42) port and you have a nice starter package (although I can't fathom (har har) an UW camera system without a strobe).
The E-PM1 has slightly less resolution than the LX7 and significantly less resolution than the RX100. Am not talking about pixels here but actual resolution of lines and detail.
The stock lens is slightly sharper than the RX100 but less sharp than the LX7
Video mode of both LX7 and RX100 are far superior than the E-PM1 and any olympus mirrorless plus you can't use the E-PM1 just with the internal strobe and the stock lens is not good for wide angle unless behind a dome, once behind a dome it become useless when zoomed
The E-PM1 sensor is now 3 years old and that is the reason Olympus is clearing out stock
For a beginner a mirrorless is too complex to handle and getting an obsolete product as a starter is a no go for me. I would rather get the Inon UWL-H100 on top of it than a dome at least you can change lenses during the dive and put a close up when you need
Still optical and image quality lag behind the LX7, G15 and RX100