Brings a new meaning to "Charlie don't surf". At this point though, you have to pretty much imagine that the military has researched any and every mode/method/means of achieving the goals of a mission. I'm sure roller blades and skateboards have been considered at some point as well.

Not sure about the military, but French police has been using rollerblades to patrol the streets of Paris.

My memory is fuzzy but I think the Australian SAS or SBS made raids on the Japanese using paddle boards in the Second World War.

It’s described in the H I Sutton book, from the website above, but I think it’s out of print now