Meanwhile at Maraamu, "the postman has arrived." Hunter reads the clue, which advises them to "tread lightly" for new fishing gear. There's no treading to be found in the challenge -- and if there were treading, it could neither be described as light nor heavy -- but we don't know that yet. I shouldn't nitpick when the clues are short, at least.
So Rotu and Maraamu show up at the challenge, where Peachy waits to tell them about their reward. Peachy got new white shorts! Each tribe has a boat which is "sitting on the bottom of the ocean floor" loaded up with 250 rocks, and tethered to an inner tube. The S15 will dive down and remove all the rocks from the boat. Once the boat surfaces, they should bail water until it's seaworthy and then race to the beach. The first tribe to place its boat on its mat wins the reward: a mask, fins, and a snorkel. Peachy points out that since some of them have already made spears, the reward will make finding food a little easier. Even without the spears, the reward would make food finding easier, so I'm not sure what he's trying to say here. Because Rotu has an extra member, they decide Robert will sit out. Either he's really sick or he can't swim because otherwise it makes little sense to leave in puny Paschal over hulking Robert. Not that sense is a prerequisite of being selected for this show.