HILO, Hawai'i — More volunteers arrived in Hilo yesterday to join search crews seeking a 24-year-old diver who has been missing off the coast of the Big Island since Sunday, and family members expected to field 10 crews to continue to scour the Puna and Ka'u coastlines today.

Mitchell Hodgson became separated from his diving partner off the Puna coast near Kehena Sunday, and was reported missing at 6:40 p.m. Sunday.

Searchers rented two private helicopters and fielded eight search teams Wednesday, and Hodgson's diving partner found Hodgson's spear gun near Kamio Point south of Na'alehu on Wednesday. That is almost 64 miles away from where Hodgson was last seen, and the discovery prompted searchers to shift south.

"It's like finding a needle in a haystack, that's how thorough it's been," said Hodgson's father, Tom Hodgson. "We're still hoping, we still hope, and that's why we've got all the search parties out. We're hoping and praying."

Mitchell Hodgson lives in Orchid Land Estates with his wife, Heather, and infant son, and has been working in a spear-gun shop in Hilo. He was swimming out to a reef at about 2:30 p.m. Sunday to fish and try out one of the store's spear guns when he became separated from his partner and disappeared, Tom Hodgson said.

Mitchell Hodgson grew up in Martinez, Calif., near San Francisco, and is an extremely strong swimmer and experienced diver, his father said. He can free dive to a depth of 100 feet, and for two summers conducted diving tours in Alaska.

He is also a master diver, a certified rescue diver and graduated with honors from Humboldt State University with a minor in scientific diving, Tom Hodgson said.

Eight search teams were at work yesterday along with Big Island Fire Department crews. Flying to Hawai'i to join in the search were Mitchell's dive master instructor from Humboldt, another close friend and former dive partner from California, and other friends from California and Idaho, Tom Hodgson said.

His two brothers and his sister also arrived yesterday to join his parents and the other volunteers in the search, Tom Hodgson said.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.