Handling open world with set special locations


Not sure where to post this as there is not really a identifiable ‘concepts’ section so please advise if there is a more appropriate place in future.

So on to the question…

I am designing an multiplayer open world TPS with core locations to be explored (mines, undersea base etc).

I have two questions relating to this…

  1. Presumably the ‘special locations’ would have to be different maps (requiring a server hop) or in ‘hidden’ parts of the main map (under the landscape etc). What is the preferred / better way to handle this ?.

  2. For locations in the side of a cliff (looking to build a sub base), do people prefer to build the location as part of the landscape, build a mesh which includes a landscape patch plus a sub base mesh and attach to the landscape or do some sort of invisible transition and push the players character to another location. I am thinking about how bet to handle swimming in to the sub base from the sea ?.

Any other constructive comments or information on other techniques to handle these items would be most welcome.