Big Lagoon is a census-designated place[3] in Humboldt County, California, 7 miles (11 km) north of Trinidad at an elevation of 56 feet (17 m).

Big Lagoon is the seat of the Big Lagoon Union Elementary School District[5] and home of the Big Lagoon School, a public K-8 school built in 1956, renovated in 1996 and now sitting off of U.S. Route 101 on 10 acres (4.0 ha) 26 miles (42 km) north of Eureka.

[6] The 2010 United States Census[23] reported that Big Lagoon had a population of 93.

27 households (50.9%) were made up of individuals, and 10 (18.9%) had someone living alone who was 65 years of age or older.

In the California State Legislature, Big Lagoon is in the 2nd Senate District, represented by Democrat Mike McGuire,[24] and the 2nd Assembly District, represented by Democrat Chris Rogers.