This data collection includes ground-penetrating radar (GPR) data and related observations collected from the NASA Goddard Instrument Field Team (GIFT) Expedition to the Icelandic Highlands in July-August 2019 and August 2021. This dataset includes observations at the Askja Volcano and caldera and Vikrahraun lava flow. GPR data were collected using Geophysical Survey Systems, Inc (GSSI) shielded bistatic antennas at center frequencies of 200 MHz, 400 MHz, and 900 MHz. Common offset surveys were conducted to investigate the subsurface interfaces. The GPR data includes raw data obtained from the instrument (as GSSI .dzt files), line shapefiles of survey locations, and interpreted ice thickness GeoPackage files with radar picks of subsurface interfaces. Also included is a context orthoimage generated from uncrewed aerial system (UAS) images over the GPR site in 2021. A high-level readme file is provided that further describes the datasets.