There's a Delta story that some desk jockey wanted a team to HALO into the mediterranean and SCUBA it to shore to deliver a radio to the US Embassy in Beirut in the 80's. The operator told him something to the effect of FU and the horse, etc. and told him: "We'll fly commercial into Jordan and then drive to Beirut to deliver your damn radio".
At any rate, Army SF also have underwater capabilities.
One thing I worry about is store keepers and home owners defending thier property, they are armed too. But I am certain any SF's unit would be able to tell the diference between law biding citizens defending private property and criminals.
The law enforcement aspect is important, unleashing SOCOM on US citizens is not likely.
There are probably 100 LEO SWAT/TRT organizations in the US that operate on the water regularly, they would be a far more appropriate choice.