Another couple enter the chic new Nava restaurant, and I squirm in discomfort. Why, oh, why, had I chosen to wear this casual skirt and flowing top to dinner? I look so out of place, as does my husband, Ed, clad in khaki shorts and a polo shirt.

The restaurant now holds a half-dozen couples, and every person, save us, is wearing the exact same thing: a plush robe and flip-flops. Clearly, everyone else at Sundara understands why they're here — to completely unwind.

"We're definitely not wearing our clothes to breakfast tomorrow," I whisper to Ed, who raises an eyebrow at this bold proclamation. Then he gently corrects me: "You mean, we're definitely wearing our robes to breakfast tomorrow." My face reddens at my gaffe, and I give silent thanks that Sundara's house rules stipulate that guests must converse quietly in most shared spaces.

Back in our room, we slip on our own soft robes, then pad over to our suitcases and zip them shut. We won't need anything in there for the next two days as we investigate Sundara Inn & Spa's major renovation.

Sundara first drew attention 15 years ago when it opened as the only kid-free destination spa in the Wisconsin Dells area — a surprising oasis in an area best known for raucousness and adventure.

The facility, tucked into 90 wooded acres, is putting the finishing touches on a 40,000-square-foot, $13 million-plus expansion dedicated to wellness. New to the property are eight suites designed for small groups, the on-site restaurant Nava, a seasonal saltwater pool, an indoor-outdoor soak pool, a fitness room and additional spa treatment rooms. Reflexology is now on the spa menu, and a new salt-therapy treatment room nods to research that links salt inhalation to improved respiratory function, better skin condition and stress reduction.

Sundara Spa in Wisconsin Dells.

The list of activities now includes traditional and water yoga, guided meditation, boot-camp fitness classes and kayak and stand-up paddleboard tours. Nutrition classes and cooking demonstrations will be added soon.

All of these activities are free for overnight guests. Day guests can tap into them by booking a spa service and paying a day usage fee.

Responding to guests

Heidi Michel, Sundara's marketing manager, said input from longtime guests was one reason for the upgrades.

The spa's repeat customers were clamoring for more pool space. And while they appreciated the resort's adults-only, no-electronics policy, as well as its requirement to use "spa voices" in common areas, they did want a few spaces where they could gather with friends and family members to reconnect. Hence, quiet conversation is allowed in the spacious new pool area, while the original infinity pool area is reserved for those wanting a more tranquil experience.

The spa industry trend toward of emphasizing wellness, not luxury — of taking care of yourself vs. indulging yourself — was the force behind Sundara's new palette of wellness experiences, which also include options such as guided hikes, mat Pilates and pontoon cruises on Lake Delton.

Competition from other Wisconsin spas may have also prompted the upgrades.

This year, the Kohler Waters Spa in Kohler unveiled an expansion, which included additional treatment rooms, more coed lounge seating near the pool, a bridal suite and a cafe with healthful foods.

Kohler also opened Lodge Kohler, with a Kohler Waters Spa, in Green Bay in 2017.

Lake Geneva's Well Spa + Salon, part of the Grand Geneva Resort, recently launched a new line of anti-aging nail services with various serum and treatment options.

Lessons learned

The next morning, Ed and I head down to breakfast wrapped in our comfy bathrobes, seamlessly blending in with the other diners. We eat breakfast al fresco on the property's new back patio, dotted with softly flaming fire pits, then change for a yoga class. Yoga is followed by a short workout in Sundara's new fitness facility, and then it's time for lunch. The afternoon brings a spa treatment for me and pool time for Ed.

I opt for a body polish and massage. A salt scrub softens my skin, a rich coating of shea body butter coats it, and a massage completes the treatment. As much as I'd like to reconnect with Ed at Sundara's pools, now is not the time. With my skin so recently rejuvenated, I opt instead for 45 minutes in the salt treatment room.

The salt room is enveloped in a soft coral hue, thanks to the pinkish salt-tiled walls and the salt crystals scattered across the floor. I settle into a comfortable recliner as fans circulate the briny air.

One of the touted benefits of salt therapy is relaxation. I'm in a blissful state, to be sure, but that might be thanks to the body treatment, this morning's yoga class or being snuggled in a robe all day.

That night, I enjoy another relaxing meal while the stars wink at us from the skies. I have bought into the notion that while this trip is an indulgence, it's also an investment in ourselves. Tomorrow, when I'm reunited with my cellphone, I'm signing us up for yoga classes as one step toward healthier living. And I may institute a new house rule: no clothes — just robes — at the dinner table.

Melanie Radzicki McManus is a freelance writer focusing on fitness and travel. She lives near Madison, Wis.