The Wondiboy Peninsula, also known as the Wondiwoi, Wandammen, Wondama, or in old sources Mandamy is a mountainous peninsula in Wondama Bay Regency, Western New Guinea. It extends northwards from the Bird's Neck Isthmus into Cenderawasih Bay, and is composed administratively of the Rasiei, Wondiboy, Wasior and Teluk Duairi Districts (kecamatan) within the regency. At the northern end of the peninsula the land breaks up into a series of islands which form Roon District, of which the largest is Roon Island.