Thailand’s largest national park is surprisingly close to civilisation but shelters an intense tangle of wilderness that sees relatively few tourists. It's primarily great for butterflies and birds. Occupying an overlapping biozone for birds as the southernmost spot for northern species and the northernmost spot for southern species, it's home to over 400 bird species. The park, except for Pa La-U Waterfall, a popular day trip from Hua Hin, closes from August to October.
The wildlife-rich Ban Krang area has a nice 2.5km nature trail. Meanwhile, Panoen Thung is a stunning viewpoint up a 4WD-only road; check whether it's open before heading out.
Wake to an eerie symphony of gibbon calls in the early morning mist at campsites at Ban Krang and near Pa La-U Waterfall.
You can reach the headquarters by minivan from Phetchaburi and Bangkok, but be sure to tell the driver you are going to Kaeng Krachan National Park and not just Kaeng Krachan town.