A Royal Navy bomb disposal unit is currently in Harwich waiting for low tide, which will allow them to carry out further assessments on the V2 missile.
Once they have the right conditions, they will clear the mud around the rocket, to see if it has a warhead attached to it. This will determine if it treated as a serious incident.
Despite the cold conditions, people from around Essex have gathered to watch events unfold. Some remember the V2 missiles coming down during the Second World War.
A six-man team from the Navy's Southern Diving Unit 2, based in Portsmouth was called out on Thursday afternoon. A 40-metre exclusion zone has been set up.
At first the RN team was sceptical because the missiles plunged to earth at more than twice the speed of sound having reached heights of up to 128 miles above the earth’s surface – so normally there was nothing left of them.
But on closer inspection it was identified as a V2. It is submerged nose down and is projecting about two feet out of the mud, around 300ft from the Harwich shoreline. It is not known whether the explosive is still present.
The bomb team is expected to remain at the scene for some time and may need to bring in a barge and dredging gear to get the missile out of the mud.
The wartime weapon – fired from the European mainland in 1944 or early 1945 – is submerged nose-down in coastal mud flats on the River Stour between Felixstowe and Harwich.
Local fishermen are understood to have known about the missile for decades and even used to moor their boats to it. Reuben Day says he remembers when the V2 was dropped on 4 October 1944. He was 15 at the time and had to take the police out to inspect it the day afterwards.
The V2 rocket was developed by pioneering scientist Werner von Braun who went on to be a key figure behind the American effort to put a man on the moon.
Built by concentration camp prisoners, more than 3,000 V-2s were launched from the continent at London, South-east England and the Belgian port of Antwerp with the aim of demoralising the civilian populace.
The missile attacks resulted in the death of an estimated 7,250 people, mostly civilians. Of these, more than 2,750 were killed in London – and another 6,523 injured.