Traveling to reykjavik for 3-4 days, and wonder what volcanos or glaciers would be suggested. We are able to rent a car/SUV to drive to open up possibilities, but if winter driving to specific spots is too dangerous, we gladly do a professional tour. Seeing both is a dream for my partner, so thank you in advance for the help.
We didn't have time to visit any glaciers/volcanos directly during our trip to Iceland at the end of Sept 2024; but we did see Geldingadalir and/or Fagradalsfjall volcano(s) spewing smoke as we went to KEF from Reykjavik. Both volcanos are on the Reykjanes Peninsula southeast of KEF, and close to Grindavik and the Blue Lagoon on the southern coast of the peninsula. In addition, we saw/went over lava fields when we did a Golden Circle Tour visiting Thingvellir National Park, Geysir/Strokkur, and Gullfoss, all of which are roughly 45 min to an hour east/southeast of the Reykjavik metro area.
If you want to take a closer look at them, take a tour. Both volcanoes and glaciers can be dangerous if you don't know what you're doing.
There are no volcano's that are erupting at the moment.
Winter driving in Iceland is only for those that have extensive experience with it, and even then you need to check the road and weather conditions multiple times a day. When we go in winter and want to go further up towards Jokulsarlon, we take a tour. For your time frame I would suggest a 2 day/1 night tour up the south coast. We have had good luck with Troll for excursions, so look at their website and see what they have for your time.
You can get both weather and volcano information here: https://en.vedur.is/about-imo/news
I myself would not mess with driving in winter, too many variables and stress. There are plenty of suggestions for tour companies in the Iceland part of this forum.
And just an fyi, many of the volcanos in Iceland are not majestic white capped peak like the volcanoes here on the west coast USA. The one that disrupted all the air traffic in 2010 looked like a pretty dull hill to me. The cooler thing I saw was where the N. American and Eurasian tectonic plates are pulling apart - not often you can stand one foot in each chunk of planet.