A horned mine is pulled ashore in south east England in 1940
An underwater diving expert estimates there are probably thousands of unexploded mines on the Suffolk coast.
A suspected UXB found near Southwold on Tuesday was not the first to be discovered in the county.
Most of the devices date back to World War II when the coast was fortified for an expected German invasion.
"I would suggest we're going to have ordnance being washed-up for the next 20, 30 or even 50 years," said Stuart Bacon, Suffolk Underwater Studies.
He has been diving for decades looking for many things such as the churches of Dunwich which were lost to coastal erosion and ordnance going back to the 16th Century.
"When you have an object weighing hundreds of pounds, it doesn't get 'washed-up'. It's not floating around.
Stuart Bacon runs Suffolk Underwater Studies on Front Street, Orford
"In the case of the
[in 2008], it became exposed by a drop in beach level.
"You've got cylindrical ones, round ones, some with horns, some that float, some that keep on the sea bed. But they're all subject to what the sea does to them.
"The ones that floated originally, could well go down, get covered with sediments and become part of the sea bed.
"What we have found as divers is the encrusting so that you get something that looks like a pipe, but it could be a bomb."
Tens of thousands of mines
It's estimated tens of thousands of mines were laid along Suffolk's coast.
The sea mines (usually the round ones covered in horns) carried 100-500lbs of explosive, while beach mines had up to 20lbs.
Cain Hegarty and Sarah Newsome wrote Suffolk's Defended Shore: Coastal Fortifications From The Air, published by English Heritage.
"The defences were heaviest in between Aldeburgh and Sizewell, because it was low-level land and would have been easily accessible for landing craft, infantry and tanks," said Cain.
"The entire coast would have been defended by barbed wire entanglements, anti-tank obstructions including concrete blocks and walls of scaffolding at the low-tide mark."
Most beach minefields were cleared by 1943 when the threat of invasion disappeared, but work continued until 1945-6 and was often carried out by German prisoners of war.
Roger J C Thomas is a military support officer working for English Heritage. His works include An Introductory Guide: Handbook Of The Defence Of Britain Project written for the Council for British Archaeology.
"We were losing a lot of shipping. It was primarily mercantile ships but also destroyers such as HMS Blanche and HMS Gypsy at Harwich in 1939," he said.
"We were laying defensive sea mines to protect British shipping channels, while the Germans were trying to lay offensive mines in those channels and at the entrances to ports.
"The sea mines were still being cleared well into the late 1950s and inevitably some will still be out there.
"Odd ones will pop-up from time to time, which is an ongoing concern for companies developing offshore wind farms and dredging.
"If anyone finds anything suspicious, they should still report it."
The coast near Bawdsey's radar station was heavily fortified in World War II
Going underwater is therefore still fraught with danger in the murky sea.
"I used to recover nets for the fishermen about 40 years ago, and this was a very hazardous operation in no visibility," said Stuart Bacon.
"The fishermen knew we were working and trawled up a bomb. They placed it on one of our markers for medieval Dunwich on the ruins we were working on.
"We went down, found the bomb, put it on the inflatable, took it to shore, put it on the beach, the police came and the navy removed the 70lb detonator.
"That was normal for us. We didn't worry particularly. We were a bit maddish in those days, but I've slowed down since.
"I think we were pushing it, but luck was with us and we got away with it.
"I have to warn new divers not to get their knife out and start prodding things.
"I've found some very large suspicious objects and left them there.
"The main danger on the beaches are 'dragon's teeth', which were iron stakes put in for armoured vehicles and landing craft which would be invading our coast.
"The council have removed hundreds and hundreds, but they're still about.
"As a diver, you would never plunge into water. You always wade gently in.
"A number of blokes have been impaled on dragon's teeth. I remember someone ran right in near Southwold sometime in the 1950s and jumped right on a stake.
"It went right through him. That was it - curtains.
"What I do advise people to do is wear socks on the beach.
"That will save a few injuries, because if you're paddling it gives you some protection."