Here are some images and information I found on these types of units.

http://www.fujitsu.com/global/services/telecom/solution/subm...

http://global.mitsubishielectric.com/bu/communication/transm...

http://www.freepatentsonline.com/6809934.html

http://en.wikipedia.org/wiki/Submarine_communications_cable

http://www.freepatentsonline.com/6534712.html

http://www.techcentral.co.za/aboard-the-ship-that-keeps-sa-c...