Fresh water.....I'll pull the port plugs, bleed some air out, put the plugs back in, pressurize. take a few breaths, check IP and if all is good there, Go Diving. Like it's predecessors, the Argonaut Kraken mechanicals are as tough as nails. Leave the panic to the porcelain Jesus regulator owners. Luis knew what he was doing when he designed it the way he did.
I have serviced Argonaut Kraken regulators that has more salt water in them than the Pacific and were still working fine. The only reason they were sent to me for service is cause the IP started to creep causing the 2nd stage to free flow slightly.
JMO and observation is that most DIN caps are garbage. Unless the O-ring seals flat against the face of the 1st stage they leak like screen doors on submarines.