Hands down the infinity pool at Marina Bay Sands.  Still haven't been, but just look at it!  It's on the 57th floor of a hotel in a gorgeous city.  Definitely urban chic and up high on my bucket list :)

Here is from far my favorite pool: le Lac Noir at Plateau d'Emparis. Cool water, stunning view and free fish massages. Not to mention tranquility :)

Hi Trevor! 

Why don't head to the warm and charming Turkey? The pools of Pamukkaleare a unique experience. Of course, you can't swim in them, but you can relax, going from the hot water to the cold one. And the view: awesome!

I'm still wondering how my best friend and I managed to weasel our way in to this luxury hotel without getting caught, but we somehow got away with it.

If you ever make it to Greece, the Cavo Tagoo hotel and spa had one of the coolest pools I have ever been in. We had a view looking out over all of Mykonos Island and far into those deep blue mediterranean waters.  

Marina Bay Sands infinity pool has the fame but many other man-made and natural pools are much more impressive, just have a look:

• Hanging Gardens Ubud Bali multi-leveled infinity pool is in the middle of the jungle and facing an ancient temple 

• Badeschiff in Berlin is a floating public pool on the River Spree open year-round

• Agua Azul Waterfalls in Chiapas, Mexico (my favorite) is a turquoise river that tumbles down natural limestone steps, forming a series of amazing cascades with pools in calcareous depressions 

• The Library Koh Samui in Thailand has a beachfront blood-red pool
  

• Bondi Icebergs Pool in Sydney is a legendary Olympic 100 years old saltwater pool facing the Tasman sea
  

• San Alfonso del Mar in Chile. The coast is too dangerous to swim so they build the world's largest swimming pool (1km length!)

• Cenote Ik kil in Yucatan, Mexico is a sacred natural hole with exuberant vegetation and waterfalls that Mayans used for both relaxation and rituals
  

• The Standard Spa, Miami Beach art everywhere, marina-style pool and the best spot to enjoy dolphins jumping at sunset

This is just a short list and I prefer natural ones, but hey the best hidden spots are yet to be discovered...

If you like the Marina Bay Sands infinity pool but think it's too crowed, then here are a few private pools that you'll love :)

- overlooking the ricefields: Villa Melati in Ubud

- overlooking the Indian Ocean: Villa Bidadari

And these are just 2 off the top of my head...

If you have a 4x4 vehicle and don't mind a steep 20 minute hike to the top of a waterfall, Gunlom Plunge Pools in Kakadu National Park in Australia are awesome!  It's one of the few crocodile free places to swim in the park.There are lots of gorges with waterfalls and swimming holes along the Gibb River Rd in the Kimberley of Western Australia.  One that I liked a lot is Lennard River Gorge. It requires a 4x4 and a short hike.

My favorite experience was at the Conrad Koh Samui.  The main pool is OK, but each villa has it's own infinity pool looking out on the Gulf of Thailand with fantastic views and sunsets.

My favorite pools?

The Devil's pool, right on the edge of Victoria Falls. You can swim there only when the water level is low. Look over the edge -- 100 meters straight down! http://www.snopes.com/photos/natural/devilspool.asp

Saline Valley Hot Springs now part of Death Valley National Park. Don't even think about going there on your own -- you will never find it. You have to have a friend who can take you there. Here are some photos -- http://leler.com/gallery/v/desert07/P3095103.JPG.html

The spa pool Little Dix Bay

May not be quite as breathtaking as the others, but for an au natural pool, Hamilton Pool Nature Preserve pool in Austin, Tx is quite a sight!

Saltwater pool at Eden Roc Miami Beach in North Miami beach. There is a lap pool and a underwater bar looking into the pool.

I love the pools at Pamukkale, Turkey, too! Magical waters there. My other 2 favorite pools in the world are the 3-tiered pools at Amankila in Manggis, Bali and the Aquatonic pool at the AYANA Resort and Spa in Jimbaran, Bali. Both pools have spectacular sea views.I've never seen any Aquatonic pool as large as the Ayana one - it's a must visit when in Bali for the best water massage therapy. Tip: time the spa visit to coincide with sunset for even more breathtaking view. Photos don't do justice - must be there to experience.

The first one that comes to mind is the gilded pool at Hearst Castle. There is more than one now that I think of it, one outdoors with ornate statues and one indoors that has fantastic tiles and is underneath the tennis courts with skylights to the pool below.

Papallacta is a hot spring in the heart of the Andes, you can watch from your personal pool the Volcano Antisana in the day or a sky full of stars in the night if you are lucky. It is no far from Quito and it is in the way to the amazonian region! 

The Pools at Pools at Ohe'o aka The Seven Sacred Pools, part of Haleakalā National Park on Maui.  Back in the '70's we visited it with my in-laws.  When we got to the area, my father-in-law asked the Park Ranger where the Seven Sacred Pools were.  The Ranger said, "There are about 15 of them,  Pick any Seven."  If the weather is good and it isn't over-run by tourists, it's a wonderful spot.  Make sure there aren't any flash floods before taking the long drive there.  The photos are from that visit, so the quality is not very good..

There is a rather secret swimming pool on top of the Changi Airport Singapore. I got to take a swim while some sort of gigantic monsoon fell on top of our heads. Probably not the most impressive pool, but it certainly was intersting!

Geothermal spa - Blue Lagoon, Iceland

I'm with Debbie. Marina Bay Sands, It's on my bucket list too.

Almost anything in Iceland. The only two I went to: Hofsós and the Lake Myvatn Nature Baths. But you could seriously just drive around the country visiting hot springs and other geothermal heated pools.

I recently went to Berlin and my friends took me to this pool in the river: Badeschiff

http://www.amusingplanet.com/2010/11/badeschiff-floating-swimming-pool-in.html

Was really cool!

There are impressive hot spring pools in India, which has medicinal values and natural .

Manikaran is one which you will find in Himachal Pradesh which is 45 KM from Kullu, it is equally a religious place to visit.

Another at Vashist within 5 km from Manali, the water is reserved you can enjoy a hot water medicinal bath.

Tattapani within a distance of 51 KM from Shimla  has similar natural hot water springs.

Similar hotsprings you will find in Ladakh.

Hanging Gardens Ubud was amazing ! !

MGM Grand Las Vegas lazy river is so cool! Wish l was there now!!!

Google The worlds deepest swimming pool. I only came across a video of it on facebook recently but it looked amazing but a little intimidating.

Try San Alfonso del Mar

huge and nice pool right next to the beach!

Covington (Tennessee)

San Alfonso del Mar en Chile