Cetti Bay and the chain of 1,000 foothills are part of Guam's Territorial Seashore Park. The area is generally considered a geological
delight with the rock formation providing clues to the volcanic origins of southern Guam. The twin hills below the Cetti Bay Overlook and to the north, called Attelong Acho, or Black
Rock, are examples of pillow lava formed underwater during ancient volcanic eruptions. To the south in the distance Cocos Island can bee seen just off Merizo village.
The coastal area around Cetti Bay has been inhabited by Chamorros for approximately 3,000 years. Latte stones and pottery shards provide the evidence. The Spanish later
created a road system which followed the coastline from Hagatna, south through Cetti Bay to Umatac. The slopes are covered with grassland, savanna, coconut trees and a ravine forest
which hides the Cetti Waterfall. Cetti Bay is on the Guam and National Registers of Historic Places.