Look up at the sky on a cloudy day and you will often see sets of parallel, equally spaced bands of clouds that are the signature of internal waves. While only visible under the right conditions, these waves are actually ubiquitous in both the atmosphere and ocean. Internal waves are generated both at the ocean surface and the seafloor through a variety of processes, and transport energy and momentum three-dimensionally through the ocean. Internal waves thus provide one mechanism for mixing the abyssal ocean and thereby sustaining the ocean’s overturning circulation. However, the sources and sinks of internal wave energy are many and complex. Mechanisms of internal wave generation, their relative importance, and the properties of the internal waves produced, are still not well understood. Furthermore, as the waves propagate through the ocean, they continually exchange energy with larger scale flows, making the energetic pathway between wave source and sink convoluted. In this seminar I will present an overview of our current knowledge of internal waves from theory, observations and ocean simulations. I will describe new models of internal wave generation and world-first regional-scale wave-resolving numerical simulations that give a detailed view of the lifecycle of oceanic internal waves.