What's the difference between the four entrances?

How many steps does it take until you get out?

How many treasures are there in the Abyssal Ruins and what's the total value of them?

What ARE the treasures in there?

Which entrance has the quickest route to the first floor?

They give you access to get Items Closer to each Entrance.

The Step Limit is about 500 Steps.

The Ruins are filled with 32 Relic items which, have a total value of $1,706,000 when sold to the item maniac at Undella Town.

Treasures for each floor: http://www.serebii.net/blackwhite/abyssalruins.shtml

There are four entrances in Undella Bay, Take the Entrance that is closest to the Shore.

The Maniac is in the Mansion at Undella Town at the West.

Hope this Helps! XD