HIGHLAND — Byron Hobbs is an experienced scuba diver who taught his sons everything he knows. That's why he forbade them from trying to dive in the "Boob Tube."

It was simply too dangerous.

So when Ashton Hobbs, 23, and B.J. Hobbs, 21, left their father's house Wednesday night, they lied to him. Family members and friends say they'd planned this dive through a 1,200-foot concrete tunnel in the Murdock Canal for several years. The two had even walked the tube last winter when it was dry, doing advance work for this very night. They had never let anyone stop them from scurrying down mountains with homemade equipment or cliff diving, so why let their dad stop them now?

They told their father they were going scuba diving in Tibble Fork Reservoir in American Fork Canyon, and Ashton turned their Suburban in that direction. But when the brothers reached the Micron plant on U-92, he turned right instead of heading into the canyon. Then he turned left onto a dirt road, headlights washing over a "No trespassing" sign and down to the irrigation canal that straddles Lehi and Highland.

The water in the canal flows north from the Provo River up to and around the Point of the Mountain, but it wasn't flowing Wednesday night. The Provo River Water Users Association turned it off earlier in the day and planned to drain the canal in the next few days. The water trapped inside the tunnel, which descends 100 feet under Dry Creek and rises again on the other side, was still, but it filled the entire tube, which is eight feet in diameter.

Ashton and B.J. surveyed the site and agreed the conditions were right for the dive. They called Ashton's wife, Tami, who looked forward to celebrating her first wedding anniversary today.

It was 8 p.m. Ashton told Tami not to worry unless she didn't hear from the brothers in two hours. Then, after ending the call on the cell phone, he slipped his scuba gear over his red wet suit. B.J. did the same over his blue suit. They waded into the water near the west entrance to the tunnel.

There, on the concrete just above the water, is a sign with red letters: "No swimming. No trespassing."

They slipped into the black water and began their descent.

Tami and B.J.'s girlfriend, Jamie Phippen, became alarmed a little after 10 p.m. They hadn't heard from the two men.

Family members drove to the canal site, where they found the Suburban but no sign of Ashton or B.J.

About 11:15 p.m., Byron Hobbs called 911.

The Utah County sheriff's search-and-rescue team rushed to the scene. Nearly 20 professionals and 45 volunteers arrived to help. But officials decided not to try a rescue dive.