For land environments, I can't think of any that have been unused, but for aquatic adventures there are a few possibilities:

• Coral Reefs - a whole maze full of creatures
• Sargasso Sea - Vast mats of impassible plants containing wrecks, hidden islands, etc.
• Deep-sea vents - the closest thing we have to an alien environment on earth..

The Plain of Jars. Thousands of giant stone jars on a plateau in Laos. Many contain bodies. No one is entirely sure who built them or why.

As far as I know, docking is generally just a simple Pilot roll.

If you're interested at getting a feel for the current version of Traveller, I'd recommend their Explorer version - only $1.00 on DriveThru: https://www.drivethrurpg.com/...

You can also try look at the free release of the old 1981 version: https://www.drivethrurpg.com/...

GURPS The Prisoner. I've never run it, and I'm still not sure how I'd run it, but I think about it often.

Completely, I'm afraid.