You can hike to this active volcano that is in the central highlands of Iceland.
You first have to drive to the parking area (this road is only accessible with a 4x4 and there are a few river crossings) and it is quite a long drive. So you can drive there yourself, but you can also just go with a travel company.
From the parking lot, it’s about 45 min - 1 hour walk to the Viti crater. But the drive and hike together are definitely a day trip.
And you can actually take a dip in "hell" (Viti means hell). So if you want to try that, bring your swimsuit.