[4] The community is in the Quinault Indian Nation in western Grays Harbor County, along State Route 109, next to the Pacific Ocean.

Point Grenville, a 120-foot-high (37 m) cliff rising from the ocean, is 2.5 miles (4.0 km) north of Santiago and is the site of the Quinault Nations' Haynisisoos Park.

The Copalis National Wildlife Refuge occupies the ocean and rocks seaward from the coastline along Santiago and environs.

According to the U.S. Census Bureau, the Santiago CDP has an area of 1.57 square miles (4.06 km2), all of it land.

This Grays Harbor County, Washington state location article is a stub.