Long before the Cullens arrived, the coastal corridor between what is now Encinitas and Solana Beach was Kumeyaay territory. The Kumeyaay people had inhabited the San Diego coastal region for thousands of years, moving seasonally between the coast and inland areas, harvesting the abundant marine resources of the lagoons and the kelp forests offshore. European contact, the Spanish mission system, and subsequent waves of American settlement progressively displaced the Kumeyaay from their coastal lands. By the late nineteenth century, the coast here was being surveyed for agricultural development — tomatoes, flowers, and avocados would become significant local industries. The Cullen subdivision in 1911 was one node in a broader transformation of the coastal landscape from Native territory to agricultural land to beach town.

Cardiff Reef, the surf break that runs along the shoreline south of the San Elijo Lagoon, is one of the most consistent reef breaks on the Southern California coast. The reef is formed by a layer of relatively flat cobble and rock that produces waves with a particular quality — longer rides, more predictable breaks — that has made it a destination for surfers since the sport arrived in Southern California in the mid-twentieth century. Professional surfer Rob Machado, one of the most recognized figures in the world of surfing, grew up in Cardiff. The lagoon to the north, San Elijo, provides a protected tidal wetland that contrasts with the exposed reef to the south. Both are characteristic features of the coastal ecology here — the lagoon filtering runoff and nurturing bird life, the reef shaping wave energy into something surfable.

Cardiff-by-the-Sea is a community within the city of Encinitas, which incorporated in 1986 by merging Cardiff with four other coastal communities: Encinitas, Olivenhain, Leucadia, and New Encinitas. Before incorporation, Cardiff was an unincorporated community in San Diego County — a status that gave it a certain autonomy but left it without its own municipal government. The merger into Encinitas preserved the separate identities of the communities even while creating a unified city. Cardiff has its own zip code, its own school district, and — most importantly to its residents — its own name. The 'by-the-Sea' suffix distinguishes it from Cardiff proper in Wales and from any other Cardiff that might arise. It is a small place that takes its distinctness seriously.

Highway 101 — the old Pacific Coast Highway — runs through Cardiff along the water, passing surf shops, restaurants, and the Sea Wall, a popular gathering spot where locals watch sunsets and the day's last sets of waves. The San Elijo State Beach campground occupies the blufftop south of the lagoon, offering camping spots with direct views of the reef and the Pacific. The entire coastal strip from Cardiff south to Del Mar passes through landscapes that feel both highly developed and still partially shaped by their natural character — the lagoon, the reef, the cliff swallows that nest in the sandstone bluffs. Esther Cullen's choice of name turned out to fit. This stretch of coast has its own identity, and it has held it.