Via Jerry Pournelle I was pointed to this really cool post from the now defunct blog (nay...an actual webLOG:) of the yacht Maiken...on August 17 2006, a large mass of debris was encountered south of Tonga
Upon closer analysis it proved to be rocks. Floating rocks!
Volcanic pumice, foamy lava that cooled with lots of gas in it....
....and where there is fresh lava there is a volcano!
A brand new volcanic island breaking the sea before their eyes!
News reports here and here.
This is just one of the neatest things I've ever seen.