They felt the ground rumble as the river was coming closer towards them, so Twilight tells the girls to put on some lifejackets she found hanging on the wall as Pinkie noticed a red inflatable boat with a yellow windscreen that was inside the shack.
Once they put the lifejackets on, the girls hop in the boat as the river destroys the boat shack with a SMASH! The girls got swept up by a giant wave and were washed away along the raging river! They soon realize the boat shack wasn't the best place to hide after all.
SpongeBob and Patrick were making their way back to the bus as they didn't notice the girls screaming while going down the river as they were too relieved to not get washed away by themselves as they can breathe underwater.