Our boat jostles against strong biting winds. We leave Listvyanka, the small shoreline town wrapped in taiga (boreal forest).
A backdrop of mountains appears phantom-like on the horizon. Snuggled in wool blankets, my husband Rick and I look out at the seemingly endless steel blue waters of Lake Baikal.
We are awed knowing we are on the oldest and deepest freshwater lake in the world, formed as an ancient rift valley 25 million years ago.
Its crescent shape is about the size of Belgium or Holland, but Baikal's claim to fame is its astounding depth - 1642 metres!
It contains 20 per cent of the world's fresh water. This computes into more volume than the five Great Lakes combined!
Our guide Valentine speaks in her native tongue to the four Russian tourists on board, then aptly switches to English for us.
"There are 333 rivers and streams flowing into the lake; only one river flows out - the Angara."
Long before scientists discovered Baikal's unique ecosystem, the indigenous Buryat peoples attributed its extraordinary characteristics to powerful lake spirits who gathered at Shaman Rock, located in the rapids where the Angara begins its outward flow.
"According to legend," said Valentine. "Before a wedding, the bride-to-be was taken to Shaman Rock to spend the night.
"Her survival meant the spirits concurred she would make a good wife and the wedding would go ahead. If she died of exposure or was swept off the gigantic rock by rogue
waves, it was best - as she would not have made a good wife anyway."
I'm thinking it wise to have a summer wedding.
"Now you men were not excluded from the spirits' judgment," Valentine added. "Those accused of a crime were deemed not guilty if alive in the morning - and if not, it was just punishment."
Lake Baikal has caused much stir in the scientific realm. The water's purity is phenomenal due to microorganisms not found elsewhere.
The most numerous are crustaceans known as the Baikal Epischura, which account for 96 per cent of the filtering of Baikal. Divers claim the water is so clear it causes unexpected vertigo from seeing so far below their feet.
Biologists have dubbed the lake and surrounding area the Siberian Galapagos for its 1,700 species of flora and fauna - of which 80 per cent are found nowhere else on the planet!
This biodiversity was given World Heritage status by UNESCO in 1996.
The only mammal to inhabit the lake is the endemic freshwater earless seal Pusa sibirica, locally called "nerpa"; estimated to have made Baikal their home for two million years.
It remains a mystery how these seals originally got to be here, considering the lake is hundreds of kilometres from any ocean; some surmise a sea-passage once linked the lake with the Arctic Ocean.
"When the lake freezes over in winter," said Valentine. "We see yet another of Baikal's marvels as the ice forms with crevasses that open and close providing breathing holes for the seals."
Since the nerpa congregate mostly in the lake's northern basin, when we are back on dry land it is off to see some in Listvyanka's Baikal Museum.
We delight in their dirigible shape of fur covered blubber, with large bright eyes and whiskered mouth at one end, and flipper tail at the other.
The main food source of these wonderful creatures is golomyanka, a native fish with translucent bodies and no scales.
The total seal population is estimated to be over 60,000, and growing since hunting them is prohibited.
By this time we are ravenous and head for the main market. People bundled in sweaters and jackets sit along stony shores - except one burly (or I should say brrrrrrly) fellow who sits cross-legged facing the lake with nothing more than a Speedo-type swimsuit.
"Now that's Siberian tough," said Rick.
Lining up at a food stall for smoked Omul, I purchase a good-sized one.
This distant relative of the salmon is yet another species found only in Baikal. Yum!
It is so delicious, salted and smoked to perfection, yet moist and tender.
We strip the bones clean in no time, and go back for more!
It is back by mini-bus to the nearby city of Irkutsk, from where our prop-plane lifts off Siberian soil at mid-night.
The "science of it all" fades as my breath catches at the mystical spectacle below. Under a full moon the silvery ripples of Lake Baikal shimmer with an eerie luminosity; a beguiling farewell from the ancient spirits.
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IF YOU GO
? More info: The Buryats, descended from Mongol tribes, live on the eastern shores of Lake Baikal rearing cattle, sheep and goats.
? Getting There: Easiest access to Lake Baikal is from Listvyanka, but accommodations in this small town are limited.
? Day trips from the town of Irkutsk (population 590,000) are popular (local buses and mini-vans
run the 70km between Irkutsk and Listvyanka.
? The Listvyanka Information Centre is near the bus/mini-van drop-off and has English speaking staff for sites/directions/boat rides.
? Companies in Irkutsk offer tours, but expensive and mostly in Russian.
? Where to stay in Irkutsk: Empire Hotel - great location & amenities (www.empirehotel.ru/).