Joe Steffen, 51, died Sunday while exploring the network of tunnels in the flooded Bell Island mine. ((CBC))

Colleagues of an American adventurer who died while exploring a flooded mine near St. John's have returned to the water, in part to honour his memory.

An autopsy is scheduled for Tuesday on the body of Joe Steffen, 51, an Ohio resident who died suddenly at the abandoned Bell Island mine site.

Steffen and other international cave divers had come to explore the mine, which a local company is hoping to develop as an adventure tourism attraction.

Vlada Dekina, a photographer accompanying the group, says she and the other divers feel the mine is safe, and that they are determined to finish the exploration they began last week.

"It's a strange feeling— you feel like you're in a car accident.… It's not going to go away tomorrow," Dekina said.

"It's probably better to finish on a more optimistic note."

Mike Fowler, who found Steffen on Sunday near the ceiling of one of the tunnels, his mask flooded with water, said he felt compelled to go back into the tunnels.

'It's probably better to finish on a more optimistic note.' —Vlada Dekina

"I'm really pleased that I got back in the water and did what I needed to do, which was finish the dive that I had planned the previous day," he said after Monday's dive.

Rick Stanley, whose Ocean Quest Adventures is hoping to develop the No. 2 mine as a world-class diving site, said the team's thoughts have been with Steffen's family.

Stanley said the team also felt, though, that finishing the exploration of the mine was important.

"Joe would have wanted us to do that," he said. "He's an explorer and an adventurer himself, and he knows the objectives we were trying to achieve here."

Stanley said the team on Tuesday will leave a memorial for Steffen.

"There's 101 miners who lost their lives down here, and every time a miner died, they put a cross on the rib," he said, referring to the roof supports in a shaft.

"Then took the rest of the day off, and that's exactly what we did [Sunday], and tomorrow we are going to put the cross on the rib," Stanley said Monday.

The No. 2 mine was closed in 1949. The rest of the mine— at one time one of the world's largest producers of iron ore— closed in 1966.

RCMP investigators are investigating the death.