Bangkok is very flat. Looking for a place to hike in Bangkok is impossible. The closest I could find was Khao Yai National Park.
I would recommend a 3 days 2 nights plan. The reason is because most of the things to do here are in the morning.
Note I visited the area on Feb 4 2024 so please note the changes during rainy and winter/summer season.
Things you must do
Obviously, hiking trails are the most important thing to do here.
Kayaking and river swimming
Kayaking and swimming in the river from the Ban Tha Chang Spring
White water rafting
White water rafting ( I didn’t have the chance to research and do this)
Other things to do
Khao Yai Art Museum
Where to stay
I recommend to rent a car. Avis and Europcar are ones I have used and would recommend.