Above ground lap pools are typically above ground pools that are long and narrow. From my own experience it takes a pool that is at least 32' long to comfortably swim laps.
There are a few models of pools that exceed 32' by enough to be called a lap pool.
The only one I have found that is truly long and narrow is the 12' x 44' pool by Doughboy. They have a couple other models that are long also. The 18' x 38' and the 21' x 41' would both be long enough to swim laps in.
Cornelius makes a couple of long oval pools also. They have an 18' x 38' and an 18' x 44'.
Most of the other pool manufactures stop at about 33' in length. If long and narrow is what you need then Doughboy is probably the brand to go with.
If space is a problem, and you still want to swim laps, you need to check out the pools by Endless Pools. They are the designers of the small pools with a current making machine mounted at one end. You stay in one small area swimming against a strong current. The water flow is adjustable and can be set to any pace you want to swim.
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