There really is, the PU map is huge and checking out all the ship's, quests, space stations, derelic ships, ship wrecks, com'arrays, refuel stations, secret probes, asteroid fields, easter eggs will take some considerable time. So much that I doubt anyone here as seen them all.
Well not in my ship's because they are small, but in Star Citizen you can walk in other people ship's so you get to enter into unfamiliar vehicles.
Have you seen the Starfarer ship?
Everyone gets lost in that ship at least once. Even a Catterpillar or a Retaliator can get confusing to walk around.
It is special because of how the Ships are modeled inside and out, allowing for players to walk inside and around them, engage in fps, use turrets etc. The seamlessly in and out of the ships is allowed by the physics grid tech which normaly doesn't exist in other games, making the vehicles moving maps where gamers can interact. (see vid above)
That's a huge derelict ship in a huge map with millions of km's. In that derelict ship you can loot stuff that earns you credits that you can then use to repair/refuel your ship, buy armour, weapons or stylish civil/bandit clothings. Some of them are tied to quest chains also. Exploring them is a lot of fun and immersive experience.