There's a lot of tidal movement under the ocean's surface, but we haven't had a great understanding of it so far. Internal tides, created around continental shelf breaks, are far more difficult to predict than the ocean waves you can see. However, MIT researchers just made a breakthrough: they've accurately simulated those hidden tides for the first time. They melded a hydrodynamic model with data from a coastal sound wave study to replicate an ocean environment (in this case, a shelf break near the US' eastern coast) with a previously unseen level of complexity, complete with background elements like currents and eddies. The technique should be useful for predicting climates and fishing populations, but it could lead to a surprising amount of technological progress, too.