"Arctic Overload" is the story featured in issue #30 of Action Man
The seaship HMS Millennium hits an iceberg, or rather an iceberg hits it brom beneath, and another comes from above. Action Man, who is onboard, deduces Dr X's involvement. Action Man dives underwater in search for Dr X's submarine base via some tunnels that seem man-made. He faces a giant squid, but manages to redirect it against Dr X's guards.
Action Man discovers Dr X could move the icebergs because he has a device that controls gravity. Two guards think they have found Action Man and attack him, but it's only his empty scuba suit as a decoy, and the real Action Man knocks them off.
Action Man uses Dr X's own gravity device against him and redirects the icebergs against Dr X's base.