You walk down the beach going easterdly and then back up going west a bit til you have an interaction with a dinosaur and can do the actual things on the island. You'll know you're there when you're in a temple with dinobro Irwinson.
That's the gist of it, it's not just a beach though the island is surprisingly pretty large - much bigger than I thought it would be. Hopefully it's a sign of things to come in regards to possible future locations being added to the game (gnome city etc. wouldn't go amiss if it followed the same standards or even went above and beyond)