This is Australia, the land of the salt-water pool and the Kreepy Krauly.
In summer, it gets hot, in case that's a surprise to anybody. People run air-conditioning (which is inefficient) and go swimming. The odd thing is that while it can get hot enough to be uncomfortable and warrant air-conditioning, that doesn't necessarily mean that the average suburban swimming pool will be warm enough to swim in.
I've been wondering for a while why there wasn't a way to hook a household air-conditioner's heat exchanger to a swimming pool. That would solve two problems in one go: 1) It would make the air-conditioner way more efficient as it has a greater temperature differential and specific heat to work with; and 2) it would heat the pool.
This should be a thing. There is a patent for this thing. There are products like this in other countries, yet I haven't found an Australian-based company that's even heard of the idea, let alone has a product.
Why is this not a thing here?
 Okay, so neither of those was invented here, but that's beside the point.