The lava eruption at Fagradalsfjall in 2021 was the most visited eruption in Iceland, with thousands of visitors per day for 6 months. To address the short- and long-term danger of lava inundating infrastructure and hiking paths, we used the lava flow model MrLavaLoba before and during the eruption. These simulations helped communicate lava hazards to stakeholders and can be used as a case study for lava hazard assessment for future eruptions in the area, which are likely to be more destructive.