A Nuclear Bomb in the Mariana Trench

We've done underground nuclear tests, and we've done underwater nuclear tests. We found out that they work, and they did some nasty environmental damage. But what if we were to take those tests to an even deeper, more remote location, like, say, the Mariana Trench? And let's make it a big bomb, like the Tsar Bomba! That's the question in the latest episode of What If? from Randall Monroe and Henry Reich. 

They take these questions seriously, so we find out what would happen. However, the world's largest nuclear bomb is no match for the deepest part of the ocean. That's not very fun, so our guys came up with a new scenario in which the bomb is equivalent to the Chicxulub impactor (which is fun to Google). That gives us results more in line with what we expect from the What If? series.