Is swimming with dolphins really a good idea?

Every day, people take boat tours in Hawaii to swim with the spinner dolphins, which are named for their above-water acrobatics.

Before my family's most recent trip to Oahu, I made reservations with Wild Side Specialty Tours, which advertised that it brings along a naturalist and limits the number of passengers on its boat; though the boat can carry 38 people, tours consist of 16 passengers. Thus one morning last August, my husband, Darryl, and I woke our two daughters at 5:30 a.m., drove to Waianae Harbor on Oahu's leeward coast and boarded Wild Side's 42-foot catamaran, the Island Spirit, to fulfill my fantasy.

We were looking for spinner dolphins, which, the crew explained, are smaller than the bottlenose variety seen on "Flipper" or in most aquarium shows and can often be found in predator-free, sandy-bottomed bays during the day. There they kick back and relax, maybe engage in a little of the activity that gives them their name (spinning leaps out of the water), before resting up for another night of hunting.

Soon, the captain got a radio message that dolphins had been spied near a power plant. As we drew closer, we were given instructions: Swim with the dolphins, not at the dolphins; don't touch them; don't splash around too much.

I didn't know it then, but some people consider swimming with wild dolphins as bad as swimming with captive ones, if not worse. In fact, swimming with wild dolphins could be considered illegal.

The 1972 Marine Mammal Protection Act prohibits any "taking" of marine mammals; i.e., to "harass, hunt, capture, or kill." "Level B harassment" was later defined in the act as "any act of pursuit, torment, or annoyance which . . . has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns."

While the research is ongoing, some experts believe that when humans come to the spinners' resting grounds, they could change the dolphins' behavior and perhaps endanger them. The spinners go to those areas "for a purpose, and that's because they need to rest," said Peter Young, who heads Hawaii's Department of Land and Natural Resources.

If the dolphins don't get adequate downtime, that could make it more difficult for them to fish and to avoid predators at night, Young explained.

"There are some initial studies that have shown some changes in the behavior of the dolphins," said Chris Yates, marine mammal branch chief for the Hawaiian division of the National Oceanic and Atmospheric Administration. "We're very concerned about the impact that these programs are having both on the individual dolphins themselves and on the dolphin population as a whole." (Young is worried about the impact on humans, as well; in 2003 a man swimming with dolphins off Oahu lost part of his foot to a shark.)

According to Trevor Spradlin, a marine mammal biologist with NOAA Fisheries in Silver Spring, Md., dolphin-swim tours cross the line "and go from passive observation and learning to interaction and disturbance." He compares the tours unfavorably with safaris, where humans observe from a distance.

"Nobody would think to get out of the safari vehicle and pet the zebras," he said.

The state doesn't have jurisdiction to ban the dolphin swims, though it can regulate commercial permits for boats that launch from harbors and ramps.

NOAA Fisheries' guidelines for observing Hawaiian marine mammals state that humans should stay 50 yards from the animals — a distance that would make swimming with them impossible. These are guidelines, however, not law. Furthermore, while many tour operators simply aren't adhering to them, many tourists are unfamiliar with them. Unless they go to NOAA's Web site and look up the guidelines — www.nmfs.noaa .gov/pr/MMWatch/hawaii.htm — it is difficult for visitors to Hawaii to know that anyone thinks poorly of the practice of swimming with wild dolphins.

At this point most tourists are likely to be as clueless as I was. Selfishly, and in retrospect, I realize that ignorance was, truly, bliss.

The captain's radio source was correct. In the distance, we could see a couple of boats, and silver flashes in the water.

The first thing I noticed when I put my head underwater was a funny noise. Maybe it was air escaping from my mask? Then I realized that the otherworldly clicks and whistles were coming from the dolphins.

I raised my head to see dolphins all over the place. As the crew, which had a better vantage point, yelled directions from the boat, "On your right!" "Look below you!" (and once, "Don't cut them off!" to an overeager group of swimmers), we gazed around, amazed at the zooming, twirling, somersaulting creatures.

The spinners are about 5 feet long and 150 pounds. They have sharper snouts than bottlenose dolphins and plumpish bodies that, though barely seeming to undulate, are very difficult to keep up with.

Twice we got ourselves in position exactly right and joined a pod of 10 or so dolphins, swimming in formation with them, feeling almost as smooth and as graceful as they were.

After a while the dolphins, who appeared to be paying no attention to us whatsoever, moved on to cavort in another part of the bay.

It didn't occur to us at the time that our short encounter disrupted the dolphins. They were clearly in a frolicsome mood when we got there, and we didn't try to touch or feed them. I can well imagine, though, that a visit later in the day would be unwelcome, that too many people in the water could be disruptive, that visits day after day would be wearing, and that some people — there are always a few — might try to touch or feed them.

Even Cullins, as owner of Wild Side, is rethinking the practice. "I don't think swimming with them in itself harasses them," she told me several months after our trip. "I think it's the quantity of the people out there and the way they're doing it."

Last month, NOAA Fisheries published an "Advance Notice of Proposed Rule Making" requesting input from the public on the spinner-dolphin swim tours. It is perhaps the first step in restricting or explicitly outlawing them in Hawaii.

Knowing what I know now, I wouldn't go on another wild-dolphin swim. I'll wait to see how NOAA's regulatory process plays out. But this is one Flipper-turned-spinner fan who can't help but hope that the agency will find some way — perhaps on a severely restricted basis — to allow the fantasies-come-true to continue.