Exactly so. I lived within 5 miles of the active lava flow. Walking on the sort of terrain you describe was de riguer. Too close to the lava and my boot soles would start melting, as the sulphur fumes fried my eyes out. Definitely the most literally "hellish" ecology I've wandered through.

The Hawaiians aren't quite as strict as we mainlanders are about safety rules either. Lots of people got injured or killed on popular stroll-from-your-car routes in the National Park, thinking "they would have this roped off if it wasn't safe!" Let The Hiker Beware.