In reply to the ant hill mob:
Depending on what kind of diving you do, take a look at DAN cover.
If you get something like the Sports Silver policy, you can add a 'Death' option for a supplement of about 70euros per year for 110,000euro cover. This only covers death whilst diving, but it allows you to take a more conventional life policy from a mainstream insurer (AXA etc.) with exclusions for diving activities.
The limits for DAN are pretty open (130m, cave, technical + RB) and do not specifically tie you to your qualification limits.
Steve