Gordon McGahey of RX Plastics said it would have the manufacturer's name on it.
Lance Brown agreed, saying such pipes were towed at sea to transport them to different locations. That explained the plug at the end and the towing point, he said.
"By towing, long lengths can be easily moved and often many lengths are towed at one time.
"This is a relatively small diameter and length compared to some that are towed. I have towed 500m lengths [of] 1.2m diameter."
Other suggestions included a boom for aquaculture, an underwater power cable conduit, the bottom of a shark net, part of an ocean plastic gathering system, or part of an old military vessel.
Environment Southland was notified of the object earlier this week by a local constable.
The concern now was identifying it, locating an owner and getting it above the tide line so it doesn't become a navigational hazard.
People are encouraged to share their ideas on what this could be on Environment Southland's Facebook page or email them to service@es.govt.nz.
