You can sometimes surface. Thousands have been killed in submarine accidents. You're under massive pressure and flying near blind in a domain where a impact cou

You can sometimes surface. Thousands have been killed in submarine accidents. You're under massive pressure and flying near blind in a domain where a impact could easily mean everybody dies. On Mars water will not be an issue. Settlements will likely be near areas with abundant water ice, but even in the extreme scenario it turns out the Martian soil is oddly 'moist.' It turns out that the Martian soil ranges from 2%-5% water by weight! This is something "The Martian" got accidentally wrong, since that discovery was made after the book was written.