Hurricane Irma was a category 5 hurricane on the Saffir-Simpson hurricane wind scale. Irma made landfall in the U.S. on Cudjoe Key (near Big Pine and Summerland Keys) in the morning of September 10, still being a category 4 hurricane, and made a second landfall on Marco Island, south of Naples, on the same day as a category 3 hurricane. Two teams from the Geotechnical Extreme Events Reconnaissance (GEER) Association, supported by the National Science Foundation, were deployed to investigate geotechnical impacts of flooding, storm surge and wave forcing in Florida in response to Hurricane Irma in September of 2017. The teams worked collaboratively with federal, state, and local organizations in Florida. This report presents the field observations of the GEER team made during the field reconnaissance from September 24 to 28, 2017. The survey region extended along the coastal zone from Cape Coral to Key West. This is a preliminary version of the report including a description of field observations and photos, and listings of additional measurements and sampling conducted. No detailed interpretations or conclusions are provided in this report, due to ongoing data analysis and an incomplete collection of detailed background information. Documented geotechnical impacts include beach and shoreline erosion, undermining of infrastructure, scour (also in locations that are usually not submerged), failure of seawalls and piers, and damage to road embankment and pavement. In addition to sediment erosion, overwash deposits also represented a severe issue covering parks, infrastructure and the interior of houses with heights of up to 1 m. The collected data document the extents of erosion and sediment deposition processes and associated damages during an extreme storm (hurricane of category 4) and inundation event. The data may provide assistance for future design and risk assessment.