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Diving the Sidon Submarine

The Sidon submarine is a dive you are likely to repeat a few times in your diving career. The sub lies perfectly intact in 36m of water and is about 15 miles away from Lyme Regis.



Slack time is vital for this dive and it is very short, the current this far out can be quite strong. Every diver should have their own SMB.



Start your dive by descending down the shot.  You are unlikely to see her until you are nearly on top of her. Her bottom is 36m, but most of the interesting sights are all on her deck or very close to it. Follow the deck until you reach the bow, drop down an have a look at the six torpedo doors (three on each side). Follow back the deck and you will see gaps in the steel hull plates. The deck drops slightly and you will find some handrails along the way. The conning tower emerges in front of you. Swim around it and follow the sub to the stern, where you can drop down to have a look at the twin prop-shafts.



Follow the sub again and swim on top of the conning tower and have a look at the “bridge”. From here you can either retrace your steps to the shot or release your SMB for your ascend.


The Sidon was scuttled at the current location in 1957 to be an SDIC (Anti-Submarine Detection Investigation Committee) target. However, that is only a minor part of her history. She was commissioned in Nov 1944, on the eve of World War II,  patrolling initially the European waters and in July 1945 (after VE day in May) she left for the Far East. She returned in 1946 and was part of the post war Royal Navy.


In 1955, she was fitted out with some experimentally MK12 torpedoes - converted MK8 torpedoes using HTP (High Test Peroxide) motor (an idea copied from captured German torpedoes in World War II). Unfortunately, the material in the MK12 reacted violently with HTP and exploded while it was in the torpedo tube, blowing open both end of the tube, flooding the submarine and sinking her in Portland Harbour. 12 crew members died plus a surgeon who was part of the rescue party.


She was raised and moved to nearby causeway, where the bodies removed and buried in a nearby naval cemetery. Two years later, in 1957,  she was pulled free and moved to her current location and is used as a sonar testing target.


For a very detailed history of her life, visit the dedicated website by clicking the button below:

HMS Sidon - Deep Quest

Sidon Submarine

Posted on 4/22/2012 by SDA Editor

The Sidon Submarine off the Dorset coast

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Key numbers

Dive type: Wreck-submarine

Length: 60m

Depth:  36m

Visibility: 10m

Location: 50°32.780'N, 02°38.400'W

Difficulty: 4 Star

Dive: 5 Stars


Sidon Submarine
Dive Log

Download a free log book page of this dive

Sidon Log Book