The fascinating secrets behind some of the many shipwrecks that lie on the seabed off the Welsh coast have finally been revealed.

Listed as protected monuments, some of the wrecks have been languishing in their watery graves for hundreds of years.

The stories behind these once magnificent ships are a window into the political and regal struggles of the times in which they sank.

Below are the stories behind the ships that met their end in the cold and troubled British waters over the years, the Daily Post reported.

The Mary, Skerries, Anglesey

The HMY Mary had the proud title of being the first royal yacht of the Royal Navy . Unfortunately it also has the title of having been the first royal yacht to sink.

It was built by the Dutch East India Company and given to King Charles II when he was restored to the throne.

On March 25, 1675, she hit a rock amid heavy fog near Anglesey while making a routine trip from Dublin to Chester. She capsized and of the 74 people on board, only 39 made it to the shore to be rescued two days later.

Charles II who was given the yacht when he was restored to the throne

In the 20th century, there were fears of looters taking some of the artefacts on board and a rescue was organised.

The artefacts, which included a bronze cannon, were taken to the Merseyside Museums who now have more than 1,500 objects from the Mary on display.

Pwll Fanog Wreck, Menai Strait, Anglesey

Another casualty of the seas around Anglesey was this cargo vessel dating back to around the 14th or 15th century.

The identity of the vessel remains unknown but it seems to have sunk with a 20 ton cargo of some 40,000 slates.

This has been a very important historical find as it tells us what was happening in the north Wales slate industry at the time of the Tudors.

Divers have discovered a treasure trove of historical insights

The slates were from the Llanberis area, split with a gouge and stacked into the wooden vessel which survives beneath its heavy cargo.

It was discovered during a marine biological survey in March 1976 and due to its potential for giving us a window into the maritime and industrial history of Wales was designated on March 8, 1978.

It is illegal to dive within 150m or interfere with the wreck without permission unless a licence is given by Welsh Government.

Tal y Bont Wreck, Barmouth, Gwynedd

This heavily armed merchant vessel sank around 1702, leaving behind a treasure trove of historical insights.

The cargo was 65 tonnes Carerra marble from Italy and it was well armed with 18 main battery, eight smaller cast iron and 10 wrought iron guns.

It has been partially excavated to reveal her bell and range of navigational and domestic artefacts.

The Tal-y-Bont shipwreck, which sank in 1702

The wreck is about 10m down and experts say the position of the anchors suggests the vessel may have been trying to run ashore when it hit an isolated patch of boulders.

It was discovered in 1978 by divers from Glaslyn and Harlow Sub Aqua Club. These divers then formed themselves into the Cae Nest Group and together with the Welsh Institute of Maritime Archaeology and History at the University of Wales in Bangor and applied for site designation and a licence to survey.

Treasures found on the vessel include a bronze bell cast with the date 1677 and a stack of pewter concreted to one of the main guns. One of these platters is shaped like a cardinal’s hat with a hallmark stamp of Lyon dated 1700.

The Tal-y-Bont wreck has been partially excavated

Coins from 10 countries suggest a date of post 1702 for the wreck. Other finds include navigational dividers, fine cutlery, a dental plate, a seal, remains of pistols, a rapier and a gunner’s rule.

The Diamond, Barmouth, Gwynedd

Not much is known about this wreck as it has only been recently discovered.

It was long known to have sunk but its location was a mystery. According to experts it was a 19th century composite wreck built of wood with copper sheathing, but with iron strengthening to the frame, with two large water tanks.

The ship was recently discovered close to the Tal y Bont wreck and is unexcavated. According to Cadw her cargo, form and even her identity is uncertain with a survey and research into the vessel ongoing.

Resurgam Submarine, Rhyl, Denbighshire

This incredible looking submarine was really ahead of its time.

It was designed by Reverend George William Garrett in 1879 and built by J T Cochrane in Birkenhead (a model can still be seen at the docks).

According to Coflien, Garrett set up the Garrett Sub-Marine Navigation and Pneumatophore Company Ltd to build the experimental craft.

He had the idea after the Russian-Turkish war of 1877, where the need for a vessel that could go under protective chain netting to destroy warships was identified.

Diving for the Resurgam, which has been underwater since 1879

The Royal Navy requested a prototype and his first design nicknamed “The Egg” was tested in Liverpool Docks in July 1878. The success of the trial led him to build the Resurgam. The vessel was built at the Britannia Ironworks, Birkenhead, for a cost of £1538.

On December 10, 1879, the Resurgam left Birkenhead for naval trials at Portsmouth under its own power but only got as far as Rhyl. After repairs, Resurgam set out again towed by a steam yacht.

However the yacht’s engines failed and when the weather worsened the towing cable between yacht and submarine broke. The submarine subsequently sunk because it could not be sealed unless by a crew member inside.

Long missing, the hunt for the Resurgam began in the 1960s when someone reported striking a large cylindrical object off Rhyl.

An illustration showing calculations for the Resurgam

In the 1990s, William Garrett, great grandson of the inventor, funded a hi-tech remote sensing survey and the final discovery was made in 1996.

Although it was mainly intact, the wreck appears to have received a massive impact which wrenched it from its resting place and moved it 8m to lie on its starboard side.

The wreck was discovered at the end of a scour suggesting that it had been dragged across the seabed. The once cutting edge submarine is now covered with white and orange plumose anemones.

For further information on the Royal Commission and its collections, visit www.rcahmw.gov.uk or www.Coflein.gov.uk, the Commission’s online database.