ABOARD HI'IALAKAI — Brian Bowen remembers the time he and three other marine biologists found themselves surrounded by Galapagos sharks during a research trip to French Frigate Shoals.

First one shark appeared. Then another. And another. Within minutes the Galapagos — known to attack humans — were aggressively circling.

The biologists knew the species well. So well that Bowen, Carl Meyer, Jeff Eble and Randy Kosaki quickly went into defense mode, pulling into a circle to watch each other's backs.

Each diver faced a different direction, Bowen said, pointing a three-prong spear out to deter attacks.

"By the time it was seven sharks it seemed that they got each other excited. Every once in a while, one would turn and come in. We would tap them on the nose with the spear and they'd leave."

The sharks continued circling for 10 to 15 minutes, then left.

Scared back into the boat?

Nope.

After the sharks left, Bowen and his fellow divers were more concerned that the sharks had forced them to waste much of their air supply, cutting into their ability to do research.

"That was half the dive," he said.

It's the ocean. There are sharks. You learn to deal with life under the sea, particularly if you're a marine biologist.

Just one day into the trip aboard the National Oceanic and Atmospheric Administration research vessel the Hi'ialakai, biologists and crew shared fascinating tales of the sea from past expeditions. The ship is on a 25-day scientific mission to the remote reefs of the Northwestern Hawaiian Islands.

Kosaki, the chief scientist, recalls the day he and others were diving on the outside of the French Frigate Shoals reef — where Hi'ialakai is to arrive tonight — when a fellow diver jabbed him.

He was alerting him to a very big female tiger shark that was headed straight for them.

Kosaki said the divers, wearing air tanks, hid themselves in a gully in the reef, but when they peeked out, the shark was still coming.

Kosaki said he suddenly saw the shark come into view and swoop down into the reef depression where he was hiding. He released a huge cloud of air bubbles. The shark turned to avoid the bubbles and cruised away.

Scientists reacted with similar cool when a fire broke out aboard Hi'ialakai near French Frigate Shoals last year.

The fire left the ship drifting helplessly and there was little those onboard could do to change the ship's path.

Commanding officer Capt. Scott Kuester said a circuit breaker welded itself shut instead of snapping open, dripping sparks and molten metal, starting an engine room fire.

"It knocked out our control system for about 24 hours. We were able to drift away from the island," Kuester said.

For zoologist Jennifer Salerno, safety wasn't her concern. She was more frustrated because when the fire broke out "we had been just about to start diving."

The ship's medical officer, Mike Futch, said the vessel filled with smoke with surprising speed. He found it was impossible to work in his sick bay, and established a medical station in the open on the ship's fantail —returning to sick bay as needed for supplies.

A day later, scientists, trying to stay busy as engineers worked on the problem, were tossing bait off the stern to see what kind of fish might rise to it in these waters.

"Unfortunately, just as we got a good chum slick going, they got propulsion again," Kosaki said.

Salerno said the professionalism of the Hi'ialakai's crew made the event far less scary than it might have been.

"I was most impressed with how well-prepared and informed the ship's crew was," she said. "They were calm and they all knew what to do."

But being at sea is not all excitement. There's also beauty and mystery.

Able-bodied seaman Bill McNally recalls serving on a NOAA ship and seeing a low, solid radar signal ahead.

From a distance it looked like a gray rock shoal, but nothing was charted there. When they got closer, it turned out to be a vast school of northern right whale dolphins, so thick that there were always enough of them above the surface to return a single large radar contact.

Operations Officer Sarah Jones, meanwhile, said some of her most memorable sights have been moonbows — the ghostly pale rainbows generated in mists by the light of the moon.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.