In addition to the more than 40 ships, six submarines, 160 aircraft and almost 19,000 military personnel taking part in upcoming biennial Rim of the Pacific naval exercises, there are some unlikely participants with unique capabilities.

They include four California sea lions and, possibly, six bottle-nosed dolphins.

The marine animals will be flown in from San Diego for simulated mine recovery in the case of the sea lions, and simulated mine detection by the dolphins.

It's a lesser-known aspect of the Rimpac exercises, which focus on high-tech sub hunting, maneuvers, beach landings and ship-sinking exercises, but whose mechanics can't match natural skills.

At 100 yards underwater in the dark, a dolphin can tell if a diver is facing away or toward the animal, said Tom Lapuzza, spokesman for the Navy's Marine Mammal Program in San Diego.

Sea lions have "incredibly good underwater hearing," and can dive to 1,000 feet to attach a recovery line to a simulated mine.

Lapuzza estimates the recovery efforts of the marine animals save the Navy $1 million a year.

The animals' efforts are "incredibly valuable" to the Navy, he said.

"There are a number of mechanical systems that work to some degree in those areas, but not as well as the Navy would like them to work," Lapuzza said. "... Unmanned vehicles are becoming better at finding mines and being able to deal with them, but they are still not as good as the dolphins are."

Rimpac 2006, scheduled to run from Monday through July 28, will bring together military forces from Australia, Canada, Chile, Peru, Japan, the Republic of Korea, the United Kingdom and the United States for training off Hawai'i.

The state Department of Agriculture processes temporary import permits for the animals, and said in 2002, the Navy brought in four dolphins for Rimpac. Other records were not immediately available.

Lapuzza said the unit that operates the mine-hunting dolphins has three sets of resources: divers, unmanned vehicles and the dolphins.

"For sure the divers and unmanned vehicles are going," he said. "They are thinking about taking dolphins, but are not sure they are going to do that yet."

The program also has its detractors. Wayne Johnson, who's on the board of Animal Rights Hawai'i, said the military's use of marine animals is a "major concern," and that they should not be "trained, confined and used for warfare."

"These animals are highly sensitive, deeply intelligent creatures, and to use them for warfare is to abuse them," Johnson said.

He has the same concerns for dolphins kept in captivity for hotel and theme park shows, which he said is like "putting an eagle in a canary cage."

"These animals need to swim free and swim long," Johnson said.

Lapuzza noted that animal-rights proponents may say it's wrong to ride horses or to milk cows and butcher beef, but another way to look at it is "we're sending in a couple dolphins for something that is safe for them to do and they'll come back fine, and in return for that, a whole shipload of sailors will go through safely."

Work to improve mechanical devices to perform the same work and replace the marine animals also is proceeding, "and we're moving ahead with that mission plan fairly soon," Lapuzza said.

In real-world scenarios, dolphins mark swimmers or mines without touching the explosive devices, he said.

The Navy started using marine mammals in the early 1960s, when military researchers began looking into how sea mammals' highly developed senses — like dolphins' sonar — could be used to find mines and do other tasks.

The up to $15 million Marine Mammal Program has 75 dolphins and 30 sea lions at its San Diego facility. Lapuzza said the animals are kept in enclosures during the day, but are released without restraint into the bay five days a week, and always come back.

Some of the animals were based in Hawai'i at Kane'ohe Bay from 1969 to 1993, when the base closure commission closed the lab and the animals were moved to San Diego.

In 1970, dolphins were deployed to Vietnam out of Hawai'i to detect saboteurs attempting to blow up an ammunition pier in Cam Ranh Bay, and in 2003 they were used in the waters off Umm Qasr in Iraq, Lapuzza said.

The four sea lions will be transported to Hawai'i by military cargo carrier at the end of Rimpac for simulated mine recovery, he said.

The sea lions are kept in cages with pools of water, and dolphins are transported in 10-foot-long fiberglass boxes suspended in a sling and enough water to enable them to float, Lapuzza said.

Reach William Cole at wcole@honoluluadvertiser.com.