“whether or not our raft would stay afloat”
Good reason to fear. If you happen to be boating over a sudden methane gas release, the bubbles effectively reduce the boyancy of the water. Your ship weighs more than the water and methane bubbles that you displace and you sink.
There is an area off North Carolina that is subject to methane eruptions. Some place in Scotland is an area called the Witch’s hole. Fishing boats are lost when methane eruptions occur and the boats sink and do not come up again.
Wasn't there some notion that this was possibly the cause for the disappearance of planes and ships in the Bermuda Triangle?