Jenna RxTravelBug
Google
Great hike to do if you're in the Myvatn Area; if you're doing this anytime after early/mid October, you WILL need crampons (up until about May I'd imagine?)
If you want to see the experience, check out my Youtube video (10 min giving you the experience/views of the rim crater hike), titled: "Coolest Crater in Iceland | Hiking Hverfjall Crater in Mývatn (A Ring Road Must!)"
We did this early October, and did not need crampons with a small amount of snowfall the night before. Anytime after, I'd imagine it'd get pretty slippery.
Takes about 15 min to do the climb up and then 1-1.5h to do the crater hike. We paid for parking (there's a sign), but I saw someone mention on google there's no cameras so you don't need to? We thought better $8 than $80!
Not challenging at hard, just the initial ascent is a steady climb. Loved this hike on the ring road. In early October, we ran into maybe 20 groups total the 1.5h there. Summers are probably crowded. Recommend sunblock and bug repellent in the summers to combat midge flies - did you know Myvatn means midge flies?!
Hiking shoes definitely recommended. Combine it with 3-4 things nearby (Dimmuborgir lava fields, Hofdi, Grotagja Cave, etc).