The Buccaneers of Backwater

It has been raining for weeks. The school is flooded and the children are sent home. Three of them, plus a dog, decide to convert their tree house into Noah's Ark. Strong currents snatch their vessel and carry it into the Atlantic Ocean. They are presumed dead, but they aren't ready to die yet. They have a much bigger fish to fry because that's where the adventure begins...
This is an adventure story for 8-11 year olds.