구경하다 means to view something as an onlooker. It's a common everyday word used about anything interesting.
탐승하다 is a very rare. I personally have never heard or seen it before. The dictionary meaning is to visit a place for sightseeing. For this meaning, however, we have 탐방하다 or 답사하다 which are fairly often heard in formal contexts.
So the related words are:
- 구경하다 = to look on (the only native Korean word in this group with a very informal feel)
- 탐방하다 = to tour or visit a place of attraction.
- 방문하다 = to visit (frequently used word for all kinds of visit)
- 답사하다 = to visit a site in person for investigation or sightseeing purposes.
- 탐승하다 (I think this is a dead word)
(탐 = visit, trace, search; 방 = visit; 문 = inquire, greet; 사 = investigate)