pulling the trigger

[Monkey Knife-fight]

I woulnd't worry too much about getting a "fancy" cold water reg. By that i mean something named "Tundra" or "Arctic" or "Glacier" or some such thing. I'm sure those are great regs but waters in the 50'sF doesn't require that. I live in Monterey and have most of my dives in cold CA waters with an Aqualung Titan reg...cheap as regs go and it works great. As for exposure protection i'd say low 50'sF is about as cold as you want to go with a wetsuit...i dive a one piece 7mm in Monterey with a vest/hood to help keep my core warm. In low 50's i'll sometimes get chilly by the end of the dive...works though.

 

[DA Aquamaster]

Cold water for practical purposes is water colder than about 45-50 degrees as above that temp you really have to work at it to freeze up a regulator.

Cold water does not always equal environmentally sealed either. The Scubapro Mk 2 for example does great on ice dives with it's TIS system and open ambient chamber as does the Mk 16.