Kep is the smallest province in Cambodia. It covers an area of 336 square kilometers with a population of 40,280 people. Along with Pailin, Sihanoukville, Tboung Khmum, Kep is one of the newest provinces in Cambodia, created by Royal Decree on 22 December 2008.

Kep is the least populous province which is surrounded by Kampot province apart from the 16 km of coast on the south facing to the Gulf of Thailand and Phu Quoc island of Vietnam.

Koh Tonsay is an island in Kep province which is 4.5 km from the southwest of Kep. This is one of the rare sea destinations in Cambodia. There are two white sandy beaches on the island, the sea here is shallow, so it is very suitable for swimming. The name of Koh Tonsay means Rabbit Island in the Khmer language. It is derived from the word Ramsay. 

Koh Tonsay is 2 square kilometers, during the reign of Prince Norodom Sihanouk, it was used as a place to rehabilitate criminals, who were used to defend the island. Today, Koh Tonsay is a major tourist destination in Kep province. There are 8 guest houses and about 5 restaurants, serving mainly fresh seafood like crabs, shrimps, and fish. During the day it can get quite busy with day tourists, which leave around 4 pm, so for the sunset, there are only a few overnight people there. Electricity runs only from 6-9pm by generators. Water can run short during the dry months (Dec-Apr) and longtail boats with big water tanks are supplying the demand.