Once you have a raft, get some meat and head on over to Herbivore Island. (Bottom right corner of the map on The Island) These guys are EVERYWHERE there. If you’re lucky, you can find one in the bay where it’s super safe, but a lot spawn by the island’s coasts as well. Herbivore Island is good in my opinion because you don’t have to worry about the threats on land, and the water is relatively safe as well. These guys are super important, as they basically open the door to underwater exploration and taming.