Tim Ericson, 30, of Marshfield, disappeared off Humarock Saturday while diving for lobsters. He is presumed dead.

MARSHFIELD - Tim Ericson spent a lot of his childhood under water, diving for lobsters up and down the South Shore.

 He learned to scuba dive when he was 12, and by 14 had caught an 11-pound lobster near Hangman Island in Quincy Bay.

 In recent years, he dove as often as possible, giving his catch to his mother, brothers, co-workers and friends.

 Ericson, 30, of Marshfield, an electrician and father of two, disappeared off Humarock Saturday while pursuing his lifelong passion. He is presumed dead.

 “He was always up for it,” said his brother, Dennis Ericson. “It was a challenge every time for him.”

 Ericson was last seen Saturday afternoon when he dove off a 28-foot boat near Fourth Cliff. He had a flag attached to him by a rope so that his spotters could see where he was in the water.

 His brother Dennis and two friends watched his air bubbles come to the surface. But after about 15 minutes, Dennis Ericson said, they noticed the bubbles stopped. They pulled on the line but it was no longer attached to Ericson. About 45 minutes later, when he still hadn’t come to shore, Ericson’s brother called the Coast Guard.

“It was just another ordinary day,” said his brother. “We went out, got him suited up.... he just said, ‘this is one of my good spots I always go down.’”

 The Coast Guard searched a 50-square-mile area during the weekend with the help of dive teams from the Scituate and Marshfield harbormasters’ offices and State Police.

 Marshfield Harbormaster Mike DiMeo said water conditions were rough that day. The current was strong and there was an unusually high tide. When Ericson dove, the tide was going out.

 “It’s very hard to dive in that kind of current,’ DiMeo said. “With the extra current, he could’ve been swept out to sea.”

 But Ericson’s brother said it was a typical dive. Ericson was a certified diver. His friend and co-worker Keith Fuller, said he dove in that same spot many times.

“It wasn’t uncommon for Tim to dive by himself,” Fuller said. “He had 100s of dives under his belt. He loved the sport. Crazy things happen. He was just a go-getter, always doing what he wanted to do. He loved it.”

 Ericson worked at Matthews Electric for 10 years and was training to become a licensed electrician. His boss said he planned to sign up for the test this week.

 “He was a great guy to work with. I could call him any time of day or night,” Scott Matthews said. “On an off day he'd come in and join us, be perfectly willing to come to work.”

“Tim was a good kid. He would do anything for you,” added Debbie Matthews, Scott’s wife. “He had the biggest heart in the world.”

 Besides diving, he enjoyed water skiing, camping, skiing, fishing and country music, his friends and brothers said. Matthews said Ericson called everyone “Smoky” or “Dude.”

 He attended Marshfield schools before enrolling at South Shore Vocational-Technical School.

 He was a lifelong member of Town River Yacht Club in Quincy, said his father, Stephen Ericson of Florida, a former Quincy firefighter. He lived with his mother, Maive Ericson, on Forest Street.

 Besides his parents and brother, Ericson leaves a son, Teddy, 11, and daughter, Kasey, 5, and another brother, Richard Ericson, of Kingston. His brother, Army Pvt. Mark Ericson, died in 1992, when he was accidentally electrocuted while serving in Seoul, Korea.

 A memorial service for Ericson will be held at 6 p.m. Monday at Town River Yacht Club, 60 Mound St., Quincy.

Sydney Schwartz of The Patriot Ledger (Quincy, Mass.) may be reached at sschwartz@ledger.com.