You and your open-circuit-scuba friends planned to dive the new wreck, but "plan the dive, dive the plan" became "plan the dive, dive the wreck, wreck the plan". At bottom by the wreck you were jumped by what looked like naval work divers with their usual CDBA rebreathers ( https://en.wikipedia.org/wiki/Siebe_Gorman_CDBA ) , but with no identifying unit badges and a tough waterfront attitude to interruptions and intrusions, including to what they nickname "pond life". Jim and Tom are efficiently secured and towed away, perhaps to an air compartment in whatever the squad have ridden to the site in, and a ride unseen from the surface to somewhere to process them. Bill unwisely tries conclusions with his compressed-air speargun, but the attack team are trained and ready for such things, and a powerful underwater ultrasound gun accounts for him. The squad know how to quickly stop open-circuit scuba bubbling which was risking showing men on the surface what is happening, and thus #2 knows to keep Jim's mouthpiece down. A look at #4's ultrasound gun shows you that you better cooperate.