This national park is quite well known and most frequent buses to the village near the park entrance run from Surat Thani or Phuket. It's a natural jungle forest with hiking trails and very authentic accommodation available. Simple huts on stilts (for when water from the river is high), surrounded by jungle life, which makes it quite literal - you can encounter giant locusts, spiders, toads, beetles in your hut, and all sorts of birds and monkeys just outside your window. Be sure to use mosquito nets while sleeping. Otherwise, it's a really authentic experience.
The lodge has a common area with restaurant, chilling area and nice jungle views. This all comes with a very friendly team of stuff who will feed you well, tell you stories, join you for a drink and organize an adventure trip for you.
After a day spent hiking in the jungle, watching monkeys and dipping in the mountain spring along the trail, we decided to go for a full day lake adventure - going on a boat through majestic rock formations to a remote lodge camp floating on the water in the middle of nowhere.
That was a truly beautiful ride and a relaxing day - swimming, chilling, having a picnic lunch, kayaking around the rock formations, spotting monkeys and birds.
Many people who go for more touristy stuff, islands and party spots don't stop in Khao Sok - yes, it's not a party capital and doesn't have a lot of luxury comforts, but it's a very easily accessible piece of pristine breathtaking nature right on the way between those more popular spots. Highly recommend!