How can I repurpose an old hot tub?

Turn it into a raised garden or move it to a back corner of the yard and use it as compost heap, worm bed if you fish!

Take the tub out of the enclosure, paint with a fish safe paint, plug all jets and drains (unless you want a way to drain it) and sink it into the ground for a pond. Put some pond plants and fish in it and one of those solar operated sprays that float on the surface (just for interest), or not, a seating area beside it with some nice landscaping and you'll be the envy of the neighbors! Here is a link for one posted here on Hometalk.

http://www.hometalk.com/diy/outdoor/pools-ponds/we-have-a-hot-tub-turned-into-a-pond-great-addition-to-my-backyard-paradise-560669?expand_all_questions=1

Plant horseradish in it....will be easy to dig out.

Hi Kathy, I too like the idea of planting something in it. If you do, put it in a place with full sun. You could put rocks in the deepest part. Then plant veggies, berries, or even herbs that you could dry and use all year. Hope this helps.

This would be great as a raised garden.

Depending on where the hot tub is located, You could possibly plug all the jets and perhaps do some additional things needed to create a Koi fish pond. If you're interested in the idea, there are online instructions for creating a healthy pond for fish.

A swimming pool for dogs!

I would sink it in the ground and make a fish pond.