Here is what you should look when looking for a hot tub, swim spa, or portable hot tubs: Verify that the seats provide comfortable support. You do not want to have to scoot down in the spa like you do in a bathtub. When sitting in any seat, the water should reach shoulder level. If it does not, you will not get full hydro therapeutic value. Stay in the spa with the jets on for at least 15 minutes. At the end of that time you will know whether the seating and jet arrangements are comfortable.