So you think you know wine spas? Think again. On April 15, the Meritage Resort in Napa, California, opens Spa Terra — the world’s first treatment center in an underground cave. It’s safe to say the 22,000-foot space — entirely submerged beneath the grounds of the resort’s private vineyard in the heart of the Carneros wine region — will be like no other. For starters, don’t expect windows. Still, the cool, subterranean sanctuary should provide plenty to indulge the senses: waterfalls, steam grottos and dipping pools. The $7.5-million interior will showcase giant oak doors, Mediterranean-style mosaics, heated floors and 10 private treatment rooms. Pregnant mothers, men and even teenagers will find special packages tailored for them. And the spa’s signature vinotherapy treatment? A grape-seed scrub, body wrap with a “wine cave mud mask,” and massage. After which, they’ll bring you a glass of wine and a cheese plate chaser.