The 500 pound World War Two device was picked up during dredging work.
Blue Flag Awards For South Coast Beaches
More than 50 beaches - including several on the South Coast - have met tough new standards to receive Blue Flag awards for this year.
Poole and Bournemouth picked up four each, so did the Isle of Wight - and there were also flags for Swanage, Hayling Island and West Wittering.
They had to meet a new 'excellent' standard under EU rules - which all beaches will eventually be tested under.
Helen Bingham from Keep Britain Tidy told Heart:
"There is a new standard coming in but the international body that runs Blue Flag has actually brought that criteria in two years early. The standard that these beaches are at now is the standard that the European Bathing Water Directive brings in in 2015.
"To meet the new Blue Flag standard they had to be twice as clean as they had in previous years. So the beaches that have lost Blue Flags, they have not got any worse; it's just that the standard has now gone to the highest it can possibly be now.
"You've got some fantastic beach managers here who're doing an amazing job keeping the beaches to such a high standard. Congratulations to all of them, their hard work has really paid off; they should be really proud and everyone who lives there should be really proud of the beautiful beaches they have."
640 men were killed when the South African troop carrier was hit by a cargo ship in 1917.
The 79-year-old man suffered a serious head injury in the Cranmer Road car park in Winton.
Two Girls Indecently Assaulted Last Sunday
Recently Played Tracks
Now playing: Non-stop hit music
Deposit £10 to get a £40 Welcome Bonus - That's £50 to play bingo, slots and more!*
Over 50 tracks to make you feel-good. New album out now...
Find your local four day weather report here.
What's happening on the roads where you are?
Make Heart the soundtrack to your day and you could be a winner with great prizes up for grabs throughout the day.
Find out more about some of the companies advertising on Heart.
Get some great ideas on how to advertise your business on radio, online and on mobile.