[1] Limestone cliffs and coral reefs surround the densely forested island, which is part of the Nino Konis Santana National Park.

[2] Jaco Island lies just off the eastern end of the island of Timor, part of the Tutuala subdistrict in Lautém District, and is separated from the mainland in front of Valu Beach by a 600 m-wide (660 yd) channel or strait (known as Jaco Strait) navigable by small vessels.

In February and March, mechi, large feasts of Meci worms (Eunice viridis) are harvested from the sea on the north coast.

[7] At least three places on the island have the remains of ancient fortifications built by the local population to protect settlements: Lai Vai, Pitilete and Honolati.

[8] The only modern structure on the island was a lighthouse from the Indonesian occupation period, a white scaffold tower about 35 m high.

It is covered mainly by tropical dry forest, fringed by strand vegetation and white sandy beaches.