The name Khao Sam Roi Yot means Mountains with 300 peaks, which describes the landscape of the park quite well. The limestone hills are a subrange of the Tenasserim Hills that rises directly at the shore of the Gulf of Thailand, with the highest elevation Khao Krachom 605m above sea level. Between the hills are freshwater marshes. However several of these marshes were converted into shrimp farms, as only 36 km² of the total 69 km² of marshes are part of the national park. 18 km² of these marshes are scheduled to be declared a Ramsar site.
Two white sand beaches are located within the park namely Hat Laem Sala and Hat Sam Phraya. Hat Laem Sala is 17 km from the park's headquarters and can be reached from the village Ban Pu either by boat or by climbing up and down over a hill for nearly 30 minutes.
Rare animals in the park include the Mainland Serow (Nemorhaedus sumatraensis), Dusky Langurs (Trachypithecus obscurus), as well as many bird species. In the ocean occasionally Irrawaddy Dolphins (Orcaella brevirostris) show up.