WINSLOW HOMER'S odyssey took him to Key West, Maine, Barbados, the Adirondacks and the North Sea coast of England. A private person, he would retreat in summertime with his box of watercolors, a release from his urban life as illustrator and oil painter.

"You will see," Homer told a friend, "in the future I will live by my watercolors." And so posterity can judge for itself with a show of 99 "Winslow Homer Watercolors," opening Sunday at the National Gallery, in celebration of the 150th anniversary of the artist's birth.

Homer's watercolors are infused with light -- often simply the white of the paper shining through to give a shimmering luminescence. As he exploited the transparency of his watercolors, he exploited daylight. Unlike his muted-tone oils that were layered in a studio, his watercolorssparkle.

Captured like vacation snapshots, there are many lovely scenes here. Early in his 30- year practice as watercolorist, Homer is where the heart is, musing upon the innocence of childhood and the fascination of women.

There are no urban children here, who could easily be found outside his New York studio -- but the apple-picking girls of New England. Liquid sun hits the tops of their sunbonnets, bounces off and splashes on the apple leaves, then drips on the ground.

Knickered boys engage in rascal pursuits, searching out gulls' eggs in a dune, hitching a ride with a catboat sailor, or lazily watching the ships at sea. They wait dreamily for the boats to bring in who knows what? Lobsters, sharks, monsters from the deep? A castaway found on a reef?

And Homer, who never married, focused on his mystery woman. In "The New Novel," she lies on her side in the grass, the picture of blissful absorption, head propped on a balled-up jacket, unaware she is being watched as she turns the pages. She is a symphony of reds with her red hair, red lips and orange dress.

In the 1870s, Homer was choosing the popular subject -- Victorian ladies in elegant repose; and like Degas he was portraying people at ordinary pursuits.

But he could not long stay away from water. A trip to England in 1881, a stay at a fishing village called Cullercoats, brought a new element to his painting: dramatic atmosphere. Black clouds. Heavy surf. Sea spray. Wind. Dependent on the sea for their livelihood, the fisherwomen of the seacoast were valiant figures. Their lives were as steady as the waves on the flat, wet beach, but there was always the threat of tragedy: a capsized boat, a lost fisherman.

And when Homer visited the Adirondacks for hunting and fishing, danger lurked there, too, for the doe. Homer focused his brush on the doomed animal when he saw her drinking from the lake, and then, a rifle-shot later, lying dead.

Watercolors seem an ineffective medium for animal gore. But in his continuing narrative of a hunt, Homer hits two high points. One is "The Adirondack Guide," where a bearded mountaineer pauses in his rowing to listen to a sudden noise. Alongside his boat, the slick blue surface of the lake reflects the deep sensuous colors of the woods. The other painting offers the comic possibilities of a boatful of baying hounds: Will they float to shore before they tip themselves over?

But while the mountain streams had their charms, it was the sea that kept calling him -- to the dazzling Bahamas, the lush Florida Keys, the Maine coast.

Although he predicted he would be best known for the medium of watercolors, we identify him with a subject. The quintessential Winslow Homer is a painting of a sailor and some young boys hanging on while the sail catches the breeze and the boat swings up on a wave. In watercolor, he called it "Sailing the Catboat." In oil, it was "Breezing Up."

WINSLOW HOMER WATERCOLORS -- Opening Sunday at the National Gallery of Art, running through May 11.