Big Lagoon is similar to other coastal features of northern California including Humboldt Bay to the south and Lake Earl to the north; an alluvial plain is surrounded by steep uplands.

Hills adjacent to Big Lagoon have been identified as the Franciscan Assemblage along the eastern shore and Pleistocene dune sandstone to the south.

[1] Studies around Humboldt Bay indicate tectonic activity along the Cascadia subduction zone has caused local sea level changes at intervals of several centuries.

[5] The coastal portion of Big Lagoon was used as an aerial rocket range by the United States Navy during World War II.

Beast" sightings refer to a series of 1980s word-of-mouth reports of a primate-like creature roaming the outskirts of Big Lagoon.

Beast, it largely resembled a sasquatch, a creature with a plethora of reports in Humboldt County and its surrounding heavily wooded areas.

The height of the creature, however, was allegedly significantly larger than the Floridian species, with witnesses reporting the B.E.P.O Beast to stand anywhere between eight and twelve feet tall.

Despite reporting the incident to an official from the county park and later following up with the California Department of Fish and Game, no footprints, DNA, or evidence of the sighting was recovered.