The twin hills of Phnom Da are spectacularly isolated Mont-St-Michel-style by annual floods, which require guests to arrive via Takeo on a 45-minute open-air boat ride. One hill is topped by a temple whose foundations date from the 6th century, although the temple itself was rebuilt in the 11th century. Exceptionally, the temple entrance faces north; the other three sides have blind doors decorated with bas-relief nagas (mythical serpent-beings).
Five artificial caves pockmark the two hills, used for centuries as Hindu and Buddhist shrines and, during the Vietnam War, as hideouts by the Viet Cong.
Phnom Da's finest bas-relief carvings are not in situ, having been taken to museums in Angkor Borei, Phnom Penh and Paris.
Nearby, on the second hillock, is 8m-high Wat Asram Moha Russei, a restored Hindu sanctuary that probably dates from around AD 700.