The hulking remains of abandoned and rusting ships rise up through the water, the glory days of sailing the world's seas and oceans long gone.

Dozens of abandoned cargo and passenger ships lie semi-submerged or completely sunken in and near the Gulf of Elefsina, an industrial area of shipyards and factories near Greece's major port of Piraeus.

Now the Greek authorities have begun to remove the ships, some of which have been there for decades, saying they are both an environmental hazard and a danger to modern shipping.

Dimosthenis Bakopoulos, Head of the Public Ports Authority says "You don't need to be a scientist to understand that shipwrecks are a environmental timebomb which degrades the environment of seaside municipalities."

" From the port of Piraeus to the island of Salamina that lies off of Elefsina, the sea is littered with 52 such shipwrecks"  Bakopoulos adds, noting that some of the ships were still leaking petroleum products into the sea.

Charalampos Gargaretas, Chief Executive Officer of Elefsina Port Authority says that in addition to the environmental risk, safety issues also lurk beneath the waves.

"There are spots where there are 2-3 shipwrecks together; where the sea waters which are navigated by other seaworthy boats. That is an absolutely major problem for navigation as a whole. Consider that the actual spots where there are shipwrecks are marked with buoys so that other boats that cross near there know that the depth is less (due to these submerged ships under the water surface) and that if not careful could collide into them. Thus, the issue of navigation is as important as the environmental issue."

But the process has been wrought with difficulties.

The owners of the ships vary from individuals to inheritors to companies registered in countries ranging from Greece to the Marshall Islands, Britain and Honduras.

Some have gone bankrupt, some are no longer traceable, officials say.

So the authorities have put in motion a process where the abandoned ships can be appropriated by the state.

Salvage companies then take over the job of breaking up the ships and removing the remains, a job they undertake free of charge to the state in return for being able to sell the metal for scrap explains Charalampos Gargaretas "the advantage lies in the value of the metal each ship is made of. So, the private investor will have to decide if he will benefit or not from selling the pieces of iron, as we call it, and make a profit. We benefit from the shipwrecks removed from here by not paying for the cost of their removal ourselves. After all our port authority does not have the appropriate machines and tools to remove them from the sea, cut the metal and remove the parts from the port."

Another problem the Greek authorities have faced is some opposition from locals who fear the environmental impact of large ships being demolished in their area.