Both have unique challenges, but overall brucethemoose is right about the overall cost comparison. For instance, we could easily have a "space elevator" equivalent to the bottom of the ocean, it'd be a fraction of the cost of maintaining a freight network to mars. Pressure is hard to deal with, but not as difficult as it is to get shit out of a gravity well as dense as Earth.
The main point is the usable resources. You'd have a damn near infinite source of usable resources at the bottom of the ocean meanwhile on Mars everything would need to be scavenged or shipped.
Pressure is way harder to deal with than a vacuum, not that i think mars is happening any time soon
Both have unique challenges, but overall brucethemoose is right about the overall cost comparison. For instance, we could easily have a "space elevator" equivalent to the bottom of the ocean, it'd be a fraction of the cost of maintaining a freight network to mars. Pressure is hard to deal with, but not as difficult as it is to get shit out of a gravity well as dense as Earth.
The main point is the usable resources. You'd have a damn near infinite source of usable resources at the bottom of the ocean meanwhile on Mars everything would need to be scavenged or shipped.
The ocean is a lot closer though, which helps