I can only surmise that Hopper might be trying to evade treasure-hungry villains who are after some artifact, or else Hopper will be fighting through underground booby traps.
It sounds like fans should whip out their Indiana Jones lassos and hats for the occasion.
Of course, “Indiana Jones-type action” is still a vague description, but one that’s also rather exciting, given the Netflix series’ Spielberg-ian tone.
How face-melting would the Upside Down’s Ark of the Covenant be?