Just found this report. Shows the dangers of exploring coastal caves in rough weather as essentially they were exploring a system very near the coast that dropped through constrictions into a sea cave. The pair of cavers were approaching the bottom of the system close to the sea when the wave surge compressed the air at the back of the sea cave section and blasted it out through the constriction with sufficient force to throw one explorer around and concuss him! I know one diver who had a similar experience when he made the mistake of diving into a submerged cave that opened into a blow hole. He managed to get back out after being rammed up the passage rather forcibly! I don't think we have extensive enough systems near the coast for this to happen to cavers but worth a thought if you are exploring new coastal cave in Ireland Scotland or Wales.