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.
To begin with, knowing how those internal tides work could help develop more advanced sonar systems that are better at accommodating underwater conditions. The simulations could also lead to better protection for offshore structures like oil rigs and wind farms, since builders can better account for once-unpredictable threats. MIT will have to conduct further tests to make sure its modelling holds up, but the chances are that you'll soon have a much clearer understanding of what happens well beneath the water line.