The Holland V submarine sank six miles southeast of the Royal Sovereign Lighthouse in 1912 and lay uncovered for almost a century.
Since it was discovered in 1995 members of the Nautical Archaeology Society based in Portsmouth have been conducting research dives on the Holland V and this year further research is being done on the wreck.
It is currently lying upright in 30 metres (100ft) of water.
She was commissioned more than 100 years ago in January 1903. However, the Holland series of submarines rapidly became obsolete and in 1912 she was being towed to Sheerness for decommissioning when she founded and sank in her current position off the coast of Eastbourne.
The cause of the sinking was believed to be as a result of flooding through a torpedo hatch and she lay undiscovered for almost a century.
The wreck is protected and monitored by English Heritage but those granted with a special licence are able to dive the wreck for research purposes.
The wreck was found by chance by Kent diver Jerry Dowd, who passed the information of the whereabouts of the submarine to renowned historian and diver, Innes McCarthy who made his first exploration dives in 2001.
The NAS has taken on the research of the wreck, continually documenting information gathered on dives conducted under licence each year.
A dive was due to take place yesterday (Thursday) and another is planned for September 11.
The NAS hopes to add further to the documented account of the wreck and monitor its condition on the seabed.
"We have been diving the Holland V since 2005 and have spent a lot of time clearing the wreck of netting and fishing lines," said Mark Beattie-Edwards, NAS operations director and current licensee of the Holland V wreck.
"This has really opened up this important wreck for further investigation, photos and research."
The Holland V was the first submarine to be commissioned by the Royal Navy and is believed to be the most intact example of the Holland series of submarines.
In addition, members of the NAS will also be diving on an 18th century wreck known as the Norman's Bay Wreck.
The wreck site was discovered in 2005 by local divers trying to free lobster pots from the seabed. Whilst underwater they encountered a number of canons and a huge anchor.
This important find was immediately reported to the Hastings Shipwreck Heritage Centre and English Heritage and recommended for designation under the Protection of Wrecks Act (1973).
Subsequent dives in 2006 and 2007 allowed for timber samples to be removed from the site for analysis so their origins and a date could be determined.
Mark added, "One thought was that this was the wreck of the Resolution which was grounded within Pevensey Bay at the turn of the 18th century, but insufficient data has been collected and there are a large number of potential wrecks it could be.
"The wreck could be one of a number of other known losses in the area most of which seem to be related to the Battle of Beachy Head in July 1690, when an allied English Dutch force was heavily defeated by the French.
"The site is littered with ballast stones and iron guns and is a haven for wildlife, including tompot blennies and large schools of bib. Common starfish are in abundance and even rare humpback prawn have been spotted on the site.
"This may be the stuff of legend and more akin to the Pirates of the Caribbean but discoveries like these are occurring around our coasts on a regular basis.
"It is hoped that this season's research dives will yield even more fascinating facts and information about the two sites."
Further information on the dives and the work conducted by the Nautical Archaeology Society are available at www.nasportsmouth.org.uk