There are two lists of things to do in Koh Samui: the one every tour desk hands you, and the one locals actually do. This is the second one.
Yes, there's the Big Buddha, the waterfalls, and the obligatory boat trip to the marine park, and some of it genuinely earns the hype. But the island also rewards the people who skip a few postcard stops and go find a quiet beach, a proper local meal, or a viewpoint without a queue.
We live here, so below you'll get the straight version: what's worth your day, what's a tourist tax, and the things to do in Koh Samui that don't show up on the laminated menu. Pick by mood, not by checklist.