Ella gave the site its name, inspired by Bayard Taylor's poem "The Fight of Paso del Mar".

[6][7] In 1885, Colonel Jacob Taylor purchased 338 acres (1.37 km2) from Enoch Talbert, with visions of building a seaside resort for the rich and famous.

[8] The United States Navy operated a Naval Auxiliary Air Facility for blimps at Del Mar during World War II.

[9] Much of the population is on the coast and nearby bluff which are vulnerable to sea level rise caused by climate change.

[10] In 2019, the city refused to develop a managed retreat strategy for moving infrastructure and population centers from the water.

[10][11][12] The Surf Line railroad tracks are adjacent to coastal bluffs some 40 feet (12 m) above the beach for 1.7 miles (2.7 km).

[15] The city wanted to require the transit agency to cover the shotcrete wall on the bluff with natural soil and native plantings.

The city council, the California Coastal Commission, and residents have opposed the district's plans to install a chain-link fence that would stop pedestrians from crossing the tracks to get to the beach.

They were working with the state to get in compliance, but until they did, they couldn't block new housing projects based on city zoning laws alone.

[21][22][23][24][25][26][27] Properties on the bluffs are subject to the impacts of climate change, such as sea level rise and coastal erosion.

The city has a climate change adaptation plan which excludes the option of a managed retreat, the strategy was recommended by the California Coastal Commission in 2019.

Del Mar's climate is considered mediterranean-subtropical with warm, dry summers and mild, humid winters.

Del Mar regularly receives heavy marine layer clouds due to its position between two lagoons and bordered to the west by the Pacific Ocean.

The historic Del Mar station once served passengers on the Atchison, Topeka and Santa Fe Railway Surf Line and the Amtrak San Diegan intercity service between the early 1900s until its closure in 1995, due to the opening of the new Solana Beach Transit Center two miles north.

San Diego Association of Governments (SANDAG) is conducting a $3 million study on relocating the rail line farther inland through the city.

The accelerating rate of sea level rise due to global warming adds urgency to the issue.