In the Crystal Isles, there's a large floating island with a massive river. There's at least six of them throughout that river. Get a couple high level aquatic or amphibious tames, I use a max level baryonix and Deinosuchus (modded), but a sarco might work. Don't just bring one creature, these things have no issues teaming up on their prey. Anyway, EXCELLENT resource for chitin and organic polymer, best I've found yet! Beware, though, you're not safe just because you're hovering over the water on a flyer, those things can JUMP!

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