Quarzite

"Why do we have to travel by subtram? Wouldn't it be easier just to land at our destination?''" "You'd think so. The atmosphere of our planet is completely pressurized, leaving all aerial travel impossible. If we attempted to land on the planet's surface, our ship would immediately implode." "''Subtram it is, then."

- Boba Fett and Major Rigosso

Quarzite was a small planet who's high atmospheric pressure rendered it's surface inhospitable.