Anyone not in decent physical condition shouldn't go into the caverns. There are other things to see and do there.
On the discovery tour, there weren't many steps, because it was mostly inclines/declines. But I will say, everything is wet inside the cavern, and fortunately there is a grit surface over most of the path, for great traction. But, the angles of some of the inclines and declines are rather steep. I'd imagine downhill stretches would be tougher with a cane than uphill. There are railings for every incline and decline I can remember navigating.
Some parts are steep and and slippery. I took my 5 yr old son the steps were a bit of a hassle. I'd recommend talking with staff so maybe they can accommodate your wife's needs. The staff is very friendly
Honestly it's like walking 8 flights off stairs in a sky scraper but more steep and wet. There are some places that are just inclines they are at about a 45° incline in some spots. Plus it is hot and humid so if you are not in relatively good condition you might not be able to do it.
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