The Yap Main Islands are considered to be made up of four separate islands: Yap Island proper ("Marbaq"), Gagil-Tamil, Maap, and Rumung. The four are contiguous, though separated by water, and are surrounded by a common coral reef. They are formed from an uplift of the Philippine Sea Plate, and are referred to as "high" islands as opposed to atolls. The land is mostly rolling hills, densely vegetated. Mangrove swamps line much of the shore, although there are beaches on the northern sides of the islands. Excluding the reef area, Yap is approximately 24 km long, 5–10 km wide, and 98 km. The highest elevation is at Mount Taabiywol in Fanif municipality on Yap island proper. The Yapese people's indigenous cultures and traditions are strong compared to other states in Micronesia.