OpenBSD has as much an association with hiking as it does security and stability. For those of us spending more time below the waterline than above, how can we leverage our favourite operating system? For those of us spending more time below sea-level than above, OpenBSD---and indeed any open source operating system---is a perfect fit in the infrastructure required by diving: photo/video editing and storage, dive planning, and dive computer analysis. In this image-rich talk, I'll discuss how OpenBSD (and open source in general) fits into the fields of free and SCUBA diving. My talk will focus on dive planning, which is integral to technical diving; dive computer analysis, integral to free and technical diving; and most of all, underwater photography, which has its place throughout. I'll pay lip service to videography, but that doesn't quite intersect with my skills. All of the images used throughout the talk---from humpback whales in the Pacific to manta rays in the Indian Ocean---were produced on a fully open source chain of components. As were all of the dives themselves, free and SCUBA, backed by an open source toolchain for planning and analysis. Beyond discussing the tools available, I'll also discuss how open source is important to the diving ecosystem itself, from hardware to nitty-gritty decompression algorithms. I'll update the EuroBSDCon 2018 version with more discussion on practical usage of tools (e.g., darktable) and new developments (e.g., the availability of Subsurface as a port, colour correction in kdenlive, etc.).