As our car sped north toward Lake Superior in January, I punched the number into my cell phone. Please, oh please, I prayed, let the lake be frozen enough so we can walk out to the sea caves. The recording clicked on and I held my breath.

"Welcome to the Apostle Islands National Lakeshore Ice Line," a male voice boomed. "Current lake ice conditions do not allow access to the mainland sea caves near Meyers Beach. To repeat: Lake ice conditions do not allow access. ... " I snapped the phone shut, a wave of disappointment washing over me.

"We can't go," I said to my husband and two daughters. The chattering in the car stopped.

We'd planned on spending much of that weekend exploring the famous Apostle Islands sea caves along Bayfield Peninsula's western shore. In summer, the caves draw visitors who paddle under their arches via kayak. In winter, people come to poke through the caves on foot, walking or even crawling on their bellies inside the intriguing niches adorned with fantastical ice formations -- if the water surrounding the sea caves is sufficiently frozen.

It used to be a fairly dependable event, the freezing of the lake in this tiny slice of northwest Wisconsin shore. Not so anymore.

"You can at least walk the Lakeside Trail and look at the caves from the top of the cliffs," said Neil Howk, National Park Service employee, helpfully. "They're beautiful there, too, but ... well, it's not the same as being able to walk into them."

Enthralling recesses

The Mawikwe (Mau-i-kway) Sea Caves, or "Weeping Woman" in Ojibwe, were formed several thousand years ago as the Precambrian sandstone gave in to the relentless pounding of Lake Superior's waters. The resulting caves -- several dozen, Howk estimated -- range in size from tiny recesses to one so immense that you could park a semi inside. A few are interconnected; one sports a natural skylight.

In winter, the ice around the caves' exteriors creates picturesque formations, affording beautiful views from the sidelines. But the real treasures lie within. "The most delicate icicles are inside the caves," said Howk. "You'll see really thin ones, and on really cold days, icicles with hoarfrost. In some places you'll see waterfalls frozen from the top of a cave to the bottom, or sheets of clear ice you can look through like panes of glass. And the ice in and around the caves can be blue, pink or white."

Although the National Park Service hasn't kept formal records of how often the lake has frozen enough to allow foot traffic to the caves, Howk said it's no longer a reliable winter occurrence. When it does happen -- as it has in the last few weeks -- it's usually in February or March. The amount of lake ice in nearby Bayfield has declined over the past 150 years, most dramatic over the past 30 years.

Cold weather alone doesn't guarantee good ice, as I'd mistakenly assumed. You also need calm water. Wave action can break up the ice and pile it on the shore. Such pack ice is rough and difficult to cross. It needs time to form into a cohesive sheet. Once that happens, it's usually safe to walk on -- assuming, of course, that the weather stays relatively cold and the winds moderate.

Making the best of it

If we couldn't walk into the sea caves, we'd at least look at them from above. Donning sturdy boots and grabbing our ski poles, we headed out from the Meyers Beach parking lot along a narrow path.

The trail wound in and out of the trees, up and down hills, and across small streams. At 1.8 miles in, we came to the first of several overlooks. We peered directly down into the cave with the skylight. It was impressive, but about another half-mile on, we hit the jackpot.

A curving expanse of brick-red sandstone stretched out before us. A half-dozen giant waterfalls had frozen in midfall. In another spot, a row of icicles stretched long, blue-white fingers from the cliff face and across the yawning opening of a sea cave, nearly touching the frozen water below.

While the visuals were stunning, the audio effects were equally impressive. Leaning against pine trees rimming the cliff's edge, we closed our eyes and listened to the delicate "plinks" the dripping icicles made, occasionally punctuated by the deep, muffled groans of the shifting lake ice. Heading back to the trailhead, our boots squeaking in the snow, it was hard to be too upset about not walking through the caves when we'd just been immersed in such beauty.

Melanie Radzicki McManus is a freelance writer living near Madison, Wis.