Photos in linked article.

“A Croatia fisherman found himself in a face-off with the US Navy after accidentally hauling a mysterious device out of the ocean.

Darko Bigava was fishing in the Elaphiti Islands, off the southern coast of Croatia, earlier this week when he pulled the object - comprised of a large orange box with metal fixtures at either end - aboard his vessel, the Marian II.

Bigava posted images of the device to social media in an attempt to identify the object, and a short time later was called on his cell phone by the US Navy demanding it back.
……
The box and an attache buoy contained almost no information on who might own it, except for a DHL shipping label attached to the side.

When reporters from Morski traced the parcel, they found that it had originate from NASA's Stennis Space Center in Mississippi.
……
A short time later, Bigava said he was contacted on his ship's radio by the US Navy and demanded the device back.

Bigava said he refused until he was paid compensation for his damaged nets, prompting a series of back and forth messages that ended with the Navy calling directly to his cell phone.

Eventually the Croatia Coast Guard agreed to pay the damages, which they said would be recouped from the US Navy.
……
As for what the device was, the orange object seems to be a weight with a sonar transponder attached to one end, and some kind of receiver attached to the other.

Such devices, known as HIPAP systems, are typically used for underwater communication and geolocation that is more accurate than traditional GPS…”

https://mol.im/a/7873631

Can't be too sensitive if they just slapped a shipping label on it and handed it over to DHL.

from the OP

This guy only wants 3k for new nets ? Sounds like the navy is getting off cheap. Buy him a new boat if they want it back that bad. Hell we piss away so much money with this government, 3k for this guy is not even a rounding error.

It's a binary seawater high stream neutron emitter.

They pose no danger as long as you don't take them out of the wate...