Well, I'll concede that "bottom of the ocean" can have varying levels of difficulty depending on what part of the ocean you're talking about. But, we've sent m

Well, I'll concede that "bottom of the ocean" can have varying levels of difficulty depending on what part of the ocean you're talking about. But, we've sent multiple humans to the bottom of the Marianas trench and we have a (shallow) ocean bottom lab, and so far, nobody on Mars. So clearly the bottom of Earth's ocean remains easier. As far as the asteroid strike topic - I think my point has gone over your head here. Asteroid strikes do happen, naturally. But if you put a lot of humans in space with the ability to push and pull asteroids around, the overall risk goes up by so many orders of magnitude that the risk of a natural strike is a negligible concern. I mean, study human history. A certain percentage of us, even the smart ones, are going to be batshit crazy at any given time, and every once in a while one of the crazy ones gets into power or hijacks a plane. And that's not counting the incidence of honest mistakes! JFK estimated that the probability of nuclear war during the cuban missile crisis was one in 3. As compared to an asteroid strike that happens once every 65 million years. Friend, the greatest threat to us is ourselves.