Hotels that make a splash

The pool at Grand Hotel Amrath in Amsterdam was like swimming inside a violet flower.

The pool at Pelican Eyes Resort in Nicaragua was like swimming on the edge of eternity -- the sun setting in brilliant orange over the Pacific.

Hotel swimming pools may not make or break a trip. But they can add to it. They can make you happy and relaxed. They can be a surprise. A bonus. A pleasure.

Must every hotel have a pool? No, says Thomas Callahan, CEO of Colliers PKF Consulting USA West and an expert on hotel valuation.

"It depends on the guest expectations. If you are going to be lounging by the pool, it should be a really nice pool. If it's a commercial hotel at the airport that's pretty much road warriors, the pool isn't that big of a deal," he says.

Because land is expensive in cities, most city hotels don't have room for a big pool -- or a pool at all. Pools can cost millions to add -- worth it if most guests will use it, but not if guests don't.

So what percentage of guests use a hotel pool?

Favorite hotel dips

Some hotel or resort pools are memorable for their location and others for their charm. They don't have to be the pools with the biggest spas or most glamour, only ones you remember with fondness. Among my favorites:

Outdoor pool, small: Pelican Eyes Resort, San Juan del Sur, Nicaragua. There actually are three pools at this resort, but the infinity pool hangs over the edge of the hill, revealing a fantastic view of the Pacific and the mountains. Shed the Central American swelter, cool off, listen to the parakeets chirping in the trees.

The only drawback? Everyone sitting at the open-air restaurant just up the steps can watch your every move -- and inspect every ounce of cellulite.

Outdoor pool, big: Many big outdoor resort pools around the world look glamorous at first but have a cheap, slapdash feel, with bumpy concrete under your feet and tiles that don't match .

Indoor pool, small: Grand Hotel Amrath Amsterdam. This large Dutch hotel has a funky, boutique-like feel. The smallish pool is in the basement, but the decor is romantic -- mysterious, sensual, dark blue walls. The womblike pool space has a ceiling of pinpoint star lights overhead; swim after dark for the best effect.

Indoor pool, big: Few hotels in the world can afford the space or cost of a large indoor pool. But the 1,300-room Beijing Marriott Hotel City Wall in Beijing, built in 2007, has an enormous pool that's 79 feet long. The serious swimmer's pool is set in a sunny glassed-in room next to a gorgeous blond-wood changing room.

When I was there in March, at least 1,000 people were staying at the hotel. I was the only person at the pool.

Family pool, big: Incredible summer-in-winter experience is at the Kalahari Resort in Sandusky, Ohio, which claims to be the world's biggest indoor water park hotel. Its wave pool alone is bigger than some lakes, and the air is 85 degrees even in the dead of winter. Bring every kid in the neighborhood. Yell. You won't bother anyone.

Family pool, small: The Traverse Victorian Inn in Traverse City is a very modest Michigan hotel. But it has a very pleasant small pool in a glassed-in area near the lobby, plus pool toys for weaker swimmers. The bottom slopes down slightly to 5 feet deep, so watch the little ones. For families with one or two well-behaved children.