Many people are afraid of that option due to the higher out-of-pocket they could pay. However, that cost is offset by lower monthly premiums and by contributions to your HSA.
Unlike the flexible spending dollars you get in a lower-deductible plan (like with a HMO), your HSA dollars do not expire each calendar year. Unused HSA dollars will carry over and you can grow them each year that you work.
In addition, HSA dollars can be invested (within the HSA plan) and so they have triple-tax benefits. You contribute the dollars pre tax; you do not get taxed on using them; and any money made on your HSA investments are also not taxed!
The catch is, HSA dollars can only be used for approved medical related expenses. Even after you retire. However, it's a nice way for those who can manage money to build a very substantial nest egg that they can use to offset out of pocket medical expenses during their retirement years.
You can always get a note from your doctor that says that you need a HOT TUB to treat your bad back/disk problem or something that would benefit from hydrotherapy treatment.
Just make sure you keep all your receipts and the doctors note recommending the treatment. In case you get audited.