Santa Monica Fourth of July Parade celebrates the national holiday and environmental advocacy.

Toddlers Salomon and Arturo Singer sat playfully in a stroller, one on the other’s lap, as they watched a parade of revelers, including marching bands, fire trucks and mounted police, stream down Santa Monica’s Main Street. Their father Ben sat on the curb nearby.

“It’s a wonderful parade,” said Ben Singer. “It’s small, it’s manageable, and you get to see everything. There’s no crowd control. It’s family-oriented. The boys enjoy the fire engines the most.”

The Singers were among throngs of spectators who turned out Sunday to celebrate the Santa Monica Main Street Fourth of July Parade. Organized by the Ocean Park Assn., a volunteer neighborhood group, the parade was marking its fourth year as a coalescing force for the community.

“It’s a way to gather people from the city, and in particular the neighborhood, to celebrate our nation’s independence,” said Ted Winterer, the association’s vice president. “People are grateful to have something like this to do on the holiday.”

Parade participants included marchers from the Santa Monica High School band, mounted Santa Monica police officers and members of the Gan Israel Day Camp, who entertained observers with their dancing, antics and acrobatics. Young people from the Lighthouse Church of Santa Monica hoisted an oversized American flag, which formed a huge canopy as it billowed in the wind.

Heal the Bay, a Santa Monica-based environmental advocacy group dedicated to protecting Southern California’s coastal waters, was honored as the parade’s grand marshal this year.

“We are happy to be part of a community that is progressive in terms of trying to help the environment,” said the group’s spokesman, Matthew King.

He added that although the parade was not political, it provided an opportunity to raise awareness about the importance of safeguarding nature, particularly in light of the devastation caused by the oil spill in the Gulf of Mexico.

Some marchers along the route of about half a dozen blocks were dressed as the Statue of Liberty. Others wore the regalia of Uncle Sam. Many donned homemade costumes depicting a theme.

Ginger Mukherjee and her daughter Liliana, 6, were draped with wavy, flowing strips of material in various shades of blue.

“We’re underwater sea creatures,” Mukherjee explained. Her daughter’s school, the Santa Monica Alternative School House, was participating in the parade and wanted to adhere to an environmental theme, Mukherjee said.

Nearby, 3-year-old Sidney Glasser clapped as she sat on the shoulders of her father, Elan Glasser.

“My daughter was very excited about coming,” said Glasser, a longtime Santa Monica resident who lives near the parade route. “It’s very, very local, and that’s good,” Glasser said.

That didn’t stop many nonresidents from coming to town. Among them were Diana and Gilbert Perez, who drove from Mission Hills in the San Fernando Valley for the celebration.

The Perezes were abuzz with excitement as they tried to find a spot on Main Street that would provide the best vantage point from which to see their son Steven as he rode among the mounted Santa Monica police, led by department Chief Timothy Jackman.

“This is so great,” said Diana Perez, beaming with pride as she pointed out her son. “This is a way for everyone to get together and remember what the Lord blessed us with — the freedom of this great country.”

ann.simmons@latimes.com