METHUEN — When divers plunge into the Merrimack River in search of submerged cars, they are met with darkness in the murky water.

But with the use of sonar equipment, the Clean River Project volunteers can look at the bottom of the river in precise detail without ever leaving the boat. 

Clean River Project founder and president Rocky Morrison said Garry Kozak, a respected expert in the underwater technology field, lent the nonprofit some equipment. He was inspired to do so after his daughter, Kara, went on her first dive with the group last week.

Morrison and his team were able to take advantage of sonar technology for Wednesday , so they traveled from the hydroelectric dam in Lawrence and through Methuen and Dracut on their way to Lowell. 

A little after 3 p.m., their journey about three quarters of the way over, Morrison said they had located at least 10 new cars in the Merrimack. 

"What the divers can do all day, this thing can do in 30 minutes," Morrison said. "It can see through the murkiness. When the divers go in, they could swim right by a car and not even know it’s there."

Another advantage of using sonar is that it provides exact coordinates for the cars, which makes it easier to find and remove them later, Morrison said. 

The 10 cars they found Wednesday brings the total number of cars tagged for removal up to about 35, but Morrison said more vehicles might be uncovered when experts review the sonar images. 

Kara Kozak grew up in Derry, N.H. and will soon move to Colorado to pursue a master's degree immunology, microbiology and pathology from Colorado State. She said her father has always focused on using underwater technology to give back, and is away now helping to look for a boat in the ocean. 

She said she was glued to the sonar screen from 9 a.m. to 5 p.m. 

"It's very exciting being able to see things that other people haven't seen or haven't known about. I think that's the coolest thing for anyone that loves to dive," she said.