A cable layer or cable ship is a deep-sea vessel designed and used to lay underwater cables for telecommunications, electric power transmission, or other purposes. Cable ships are distinguished by large cable sheaves for guiding cable over bow or stern or both. Bow sheaves, some very large, were characteristic of all cable ships. Newer ships are tending toward pure stern layers with stern sheaves only as seen in the photo of CS Cable Innovator at the Port of Astoria on this page. The names of cable ships are often preceded by "C.S." as in CS Long Lines.
The first transatlantic telegraph cable was laid by cable layers from 1857–58. It briefly enabled telecommunication between Europe and North America before misuse resulted in failure of the line. In 1866 the SS Great Eastern successfully laid two transatlantic cables, securing future communication between the continents.
In addition to cable layer ships, there were cable repairing ships which were tasked with finding and repairing under sea cables that broke or for whatever reason became inoperable. 
- List of international submarine communications cables
- Optical fibre
- Submarine communications cable
- Submarine power cable
- http://atlantic-cable.com/Cableships/Monarch%284%29/ | History of the Atlantic Cable & Undersea Communications
- http://www.navsource.org/archives/09/27/09270209.jpg | NavSource Photo, USS Neptune (ARC 2) bow sheaves
- http://atlantic-cable.com/CableStories/Parrish/index.htm |Leo Parrish and CS Long Lines (working TAT-5)
- http://www.hmts-alert.org.uk/ |A short introduction to cable ships - See HMTS.
- http://atlantic-cable.com/Cables/speed.htm | History of the Atlantic Cable & Undersea Communications - Cable Signalling Speed and Traffic Capacity
- Popular Mechanics, April 1930, pg 621 various drawing and cutaways of cable repair ship operations
|Wikimedia Commons has media related to Cable-laying ships.|
- International Cable Protection Committee - Cableships of the World
- Photos of commercial cable layers
- History of the Atlantic Cable & Undersea Communications
- "Cable Laying Ship Is Floating Wonderland", July 1932, Popular Mechanics