Khai Yai is a national park in Thailand.
Hitching In, Out & Around
Hitching is very easy here, even when there's more than one of you. Particularly on weekends, lots of wealthy Thais from Bangkok drive up here in their cars, so there's regular traffic.
At one point, when we wanted to walk to a place on the road we'd seen heaps of monkeys, every second car was stopping & offering us a lift, even though we weren't hitching.
You may be sitting in the open air of the back of a ute/truck with some lifts, but no doubt you'll be with 4 or so other friendly people who are also sitting there!
Good-value songtheaws (open trucks with 2 benches in the back) go between Pak Chong & the main entrance of the park. However, the park entrances are more than 10kms downhill from any of the walking tracks, waterfalls, camping grounds etc. and there is no public transport at all within the park. So hitching time it is!
Places to Visit
Waterfalls: Heo Suwat in the monsoon season is a great waterfall. It's alright for swimming & very refreshing after a hike in the jungle! There's a rope swing from a tree into the pool at the bottom. Remember that the thais are conservative dressers, and people will normally just wear their clothes swimming. Bikinis will get lots of looks from the Thais! However there are often other foreigners there wearing western-style bathers too.
Walking tracks connect some of the waterfalls & camping sights.
Salt licks are dug up patches of earth to reveal the salty clay, which the elephants love. A great opportunity to see a herd of wild elephants!
Things to Avoid
Nighttime Animal Safari: This ends up being a drive at night just spotlighting all the deer you can see in the day. Rarely do people see anything apart from grazing deer.
Secure you tent & food! Monkeys will raid your tent, and run away with your food! Deer will also have a go at anything left outside or at the opening your tent.
Accommodation and Sleep
Affordable accomodation is quite bad in Khao Yai.
Dormitory may be the cheapest option, but look at it before you say yes. It consists of wooden plank beds (very uncomfortable unless you have your own mattress/lilo) in a room with no lockable doors, and the bathroom (that you share with however many dozens of school kids are there) gets cleaned once a century.