EMPIRE, MI - Bright sunshine, blue sky and wispy white clouds - it was a perfect day at the beach. A spectacular, wintery, cave-tastic day to explore the frozen formations of Lake Michigan.

On a summer day, sand castles grab the glory. But on Saturday, Feb. 28, ice caves ruled.

Cars filled the parking lot at Empire's public beach, and dozens of explorers ventured onto the ice. It was slick in spots - this is ice, after all. The wise ones wore crampons, sharp-toothed cleats that attach to the bottom of your boots. The rest of us just watched our step.

On the frozen lake, hummocks of ice towered like sand dunes. Openings yawned wide, creating ice caves that looked as solid as rock and downright cozy. In others, overhangs stretched out, showing off icicles that glinted in the sun.

Two ice dunes looked as if they had been smashed together. Between them ran a jagged crevice about a foot wide and a couple of stories high.

Beneath one ice hummock ran a tunnel, a tiny passageway just big enough for a small but intrepid explorer. At the top of another hill, there was a wide, deep hole lined with sandy ice. Many of the ice dunes are dotted with rounded boulders.

Some stretches of the lake lie as flat and smooth as an ice rink. In other spots, it looked as if rolling waves had been suspended mid-roll. In the clear stretches, we saw what was beneath the ice - more layers of ice.

About 100 yards out, a jagged wall stood guard. Slabs of ice had been broken and slammed against each other.

Every now and then, a crack rang out. A little reminder: This is a lake, and the lake is alive.

On the north end of the beach, Shalda Creek trickled in. The narrow patch of open water evoked images of summer.

In less than three months, it will be Memorial Day. We will dip our toes in the water and the kids will dive in, and we will look out over a vast expanse of blue.

But for now, the Big Lake belongs to winter. Icy, snowy, beautiful winter.

And it's still a perfect day for the beach.

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• Lake Michigan's beautiful ice in 40 aerial photos

• Aerials of Lake Huron show near-historic ice cover with ribbon of open water

Sue Thoms covers health care for MLive/The Grand Rapids Press. Email her at sthoms1@mlive.com or follow her on Twitter, Facebook or Google+.