CARLSBAD -- Most teachers would have a hard time finding volunteers if they suggested extra classwork on a school holiday. But Tom Muilenburg, a science teacher at Carlsbad High School, can draw a crowd without even trying.

Muilenburg teaches marine science at the Carlsbad campus, where he offers an optional scuba certification program in addition to the regular oceanography and marine biology schoolwork.

On Veterans Day, Muilenburg and six of his students spent the holiday diving along a stretch of beach in Carlsbad to collect ocean-bottom data for a research project.

"These guys love the ocean," he said, adding that the students spend so much time snorkeling and surfing on their own that they jump at the chance to go diving.

Muilenburg said many of his students have gone on to study marine science at schools such as UC Berkeley and UC San Diego, but others are attracted to his class simply because they love the water. On Thursday's Veterans Day dive, there was an aspiring marine biologist as well as a future mechanical engineer who said he just loves to fish and surf.

Nick Norton, a junior, said he wants to be the captain of a sport fishing boat some day.

"I figure the more exposure to the water I can get, the better," he said.

With so many local schools so close to the ocean, adding scuba diving to a marine science class seemed like a natural idea, said Muilenburg, who has taught at Carlsbad High for 11 years. Even so, he said, he's not aware of any other area high schools that have tried it.

"I do it because I love it," he said, admitting that there's a lot of equipment he needs to handle.

Muilenburg offers scuba classes as an extra-curricular program at the school. He is certified to teach scuba and provides the diving gear for his students.

Students come out of the class with an official scuba diving certification. Some of the juniors who take his class continue to go on dives in their senior year.

The class has been exploring a reef that was created by the boulder-covered pipeline that runs out into the Pacific Ocean from the Carlsbad sewage treatment plant.

Muilenburg describes it as a "nice reef" with "a lot of (interesting) stuff growing on it."

"They do a good job cleaning the water here," he assured his students. "Not like down in San Diego."

To collect their samples, the scuba class swims out 200 yards to where the water ranges from 20 to 40 feet deep.

They're studying invertebrate life on the reef and collecting what Muilenburg calls "census data," to see how it might change over the years.

They have only been studying this particular reef for two years but plan to compare it with the natural reef farther up the coast that they have been studying since the scuba certification program started six years ago.

After an hour underwater, the student divers came plodding out of the surf, carrying their flippers and reporting on the marine life they spotted.

Among their finds was a sheepshead, tons of tiny lobsters and one large, tasty-looking crustacean that would have been dinner but for a scary sea urchin nearby.