This is why most astrophysicists agree if something the size of wiped out the dinosaurs struck, far off fishing villages would be the last of us to die off, if they even did. They could survive the worst of the atmospheric broil and would have access to the food source that would be the last to go (fish). They'd have to figure out a way to sustain off fish until land life could return, but it'd be possible, though highly unlikely. It partially depends on where the impact is... obviously nothing is surviving in oceania if it's a Pacific strike, but the Caribbean might; and vice versa. Most land strikes, while causing 10.0's and a few 11.0's, would be much easier to weather in the ocean. (An 11.0, if you're on land, and close enough to the epicenter, which is rather large, would put your legs through your chest cavity). Then you have the Falkland Islands, Antarctica bases, the international seed bank... etc.
I wouldn't bet on it though.
I wouldn't bet on it though.