Local police said the four Thai women were in a group of 46 tourists who visited the waterfall and all of them wore life jackets.
The group was about to leave the area when the four women decided to walk across the rocks at the top of the waterfall, to take some final photos before their departure.
They were being careful and holding each other's hands, when one of them slipped and pulled the other three down and over the waterfall.
They fell into an area of the river where the current is very strong there are whirlpools and underwater rock holes.
All four women were trapped underwater. Three life jackets were washed up on the surface of the river.
Chaloempol Hongyon, head of a local rescue team, said the strong current delayed their attempts to reach the women. It took two hours of battling against the river in a rescue boat just to reach the scene of the tragedy.
The water was clear and rescuers saw one body trapped in a hole about five metres under water. The other three bodies were in shallower water and still holding hands. It took rescuers until 5.30pm Sunday to retrieve all four bodies.
The ill-fated holiday-makers were identified as Mrs Nathamon Lekbamrun, 39, Miss Narumol Kamolpatana, 33, Miss Yuwadee Khongpichiansri, 29, and Mrs Papassorn Lohananthachai, 37.
The group of the 46 tourists had arrived at the reservoir of the Srinagarindra dam for a rafting trip on Saturday. Their rafts were driven upstream to the waterfall on Sunday.