This paper explores the lessons learned from using a high-resolution terrain database, and the establishment of an online repository for its distribution, in order to support Operation Blended Warrior (OBW) 2017. OBW has been a multi-year, annual Live, Virtual, & Constructive (LVC) special event, conducted during the Inter-service/Industry Training, Simulation, and Education Conference, focused on exploring the challenges in using LVC simulations for training. To support OBW 2017, baseline terrain databases, runtime formats, and 3D models were shared with OBW participants via a common online repository. This proved to be extremely valuable, as previous OBW exercises required participants to access multiple disparate and often ad hoc repositories to locate terrain source data and database products. Despite using a single terrain distribution source, there were still clear difficulties in terrain interoperability: multiple systems used by various organizations – both government and industry – resulted in variations in appearance and quality of the terrain and models displayed; some hardware was insufficient for processing or displaying the high-density database; and anomalies such as floating buildings, broken roads, avatars walking in air, vehicles driving through trees, and avatars on ship remaining stationary while the ship was moving up and down (ankle deep in steel!). We explore the causes of the problems – whether hardware-related system problems, terrain development glitches, interoperability standards or compatibility issues, or software configuration settings. These problem areas are evaluated from a technical perspective and also from the perspectives of several OBW participants. Finally, we explore the impact on “fair fightâ€� interoperability vice purely visual anomalies and highlight how to avoid them.