Once you've planned, executed and survived an active vacation — hiking, biking, kayaking, you decide — a week on a beach lounger seems decidedly ho-hum.

Personally, I'm an adventure travel slut. Show me a backpack, and my toes start to tingle. I've been trekking in Tibet, dog-sledding in Lapland, rafting in Costa Rica, bicycling in France, scuba diving in Mexico — I'll stop now — and the more adventures I take, the more enthusiastic I am about recommending them to others. Others being you, dear reader.

Why? Because active vacations are fun, exciting, totally distracting and sometimes life-changing. They lure you into nature, where all the good stuff happens. Mountains, rivers, forests, deserts — nature soothes and heals in a way the blackjack tables at Caesar's Palace never can. When you challenge yourself outdoors — physically, mentally, emotionally — you discover new things about yourself, including how effortless it is to wake up at 5 a.m. when nature is calling.

My favorite kind of adventure is the one I've never had before, which is why I leaped at the chance to go whale-watching in Baja Mexico last week. It wasn't just whale-watching — it was amazingly close encounters with the big blue whales, the largest animals to ever live on Earth, even bigger than the dinosaurs. And it wasn't just the blue whales; it was also a week of inspired yoga with two of my favorite teachers, Tias and Surya Little (www.prajnayoga.net). And it wasn't just deep breathing and oceanic meditation, it was time on the water with a wildly enthusiastic whale expert named, of all things, Michael Fishbach, founder of Eco-Interactions (www.ecointeractions.com).

"These guys are a complete mystery," Michael says about his pals, the big blues, after more than 20 years of research. "Why do they keep coming back to Baja? When do they give birth? And where? There's so much we really don't know."

What we do know about the big blue whales is mind-boggling. They weigh up to 150 tons. The heart of a blue whale is the size of a Volkswagen beetle, and their arteries are large enough for a child to crawl through. They can swim at speeds up to 30 mph, can dive down to 10,000 feet and can hold their breath up to an hour. The average length is 70 to 85 feet, but they can grow to 100 feet or more. Their life span is 60 to 70 years, possibly more, maybe less.

They eat up to 4 tons of krill a day — tiny, shrimp-like creatures — and saddest fact of all, they are a seriously endangered species. Thanks to illegal whaling, pollution, fishing nets, cargo ships and killer whales, there are only about 10,000 blue whales left on the planet, which is why Michael and some colleagues started the Great Whale Conservancy under the umbrella of Earth Island Institute.

You can do your part by visiting www.eii.org/gwc and learning about his campaign, but the best way to get a feeling for what magnificent beasts they are is to do what I was lucky enough to do, and go out with Michael at 6:00 in the morning on the Sea of Cortez — with the full moon setting on one side of the bay and the blazing Mexican sun rising on the other. And watch for spouts. And just listen.

"HHH-A-A-AUHHH" is my lame attempt to repeat a sound I'll never forget — the exhalation of a big blue whale rising to the surface to take a breath. Wow. How can I explain? The blues have a presence.

Energetically, you feel a mysterious connection to an extraordinary being. When they fluke — their huge tails rising high in the air as they dive deep — it feels like a blessing. Blues are notoriously calm and trusting, neither threatened nor threatening, and their brains function more highly then many of our elected officials.

Some of the 20 to 30 blue whales we saw came within 15 feet of our little boat. So close! I gasped in amazement. I imagined myself on their backs, diving deep into my own fears of the sea. I felt inexplicably overwhelmed with joy and gratitude. This never happens at Disney World.

ENERGY EXPRESS-O! BIG BIG BIG LOVE

"I've fallen in love with these animals over the years, and I feel I want to help save them. To me, it's an honor to see them." — Michael Fishbach

Marilynn Preston — fitness expert, personal trainer and speaker on healthy lifestyle issues — is the creator of Energy Express, the longest-running syndicated fitness column in the country.