Great day trip! I booked online the night before and had no problem being added to the trip leaving early the next morning. My hotel was close to the Insea pier, so I opted to meet there a half hour before the tour started (met at 8:30 for 9am tour). When I checked in they asked for my lunch preference - chicken or vegetarian.
I saw mixed reviews about the snorkeling - I went in with low expectations and was pleasantly surprised. The coral was bleached, which is sad, but there were still a lot of cool fish to see. The two hikes were awesome. I didn’t have time to do both the hike and kayaking on the main island - the top viewpoints on the hike are pretty epic, so I’m glad I did the hike, but it involved a lot of super steep stairs, taking up a lot of time and not leaving enough for kayaking. I’d suggest going up to only the first couple viewpoints if you want to also kayak, rather than all the way to the top. The emerald lagoon was cool - fewer, but steeper steps that were basically ladders at some points. Saw dusky lemurs on the hike up to the viewpoint on the main island - very cool! And there were hornbills on the island where we had lunch.
Overall, I’d recommend the trip, but it is a lot of time traveling between places. It takes an hour to ride from Koh Samui to the national park, plus 15-30 min between the three stop, so almost half your day is traveling. The speedboats each had at least 30 people - they’re big so it didn’t feel super packed, but we’re all sitting sideways, which isn’t the most comfortable for a long journey. And we had some rough waters a few times - be prepared to be thrown around a bit and to get splashed (even though the boat had an overhead cover). Some kids got seasick - I wear pressure point bands to help avoid getting motion sick and they worked great for me, including on this trip.
The guides were great - we had 5 guys just for our group of about 30 and they helped with getting on and off the boat, handing out gear, helping people that got seasick, and taking tons of photos for everyone. They were good about handing out water throughout the day (though I wish there was a better option than a million tiny single use plastic bottles).
