75 metres below the sea off the northern tip of the Swedish island of Öland, lies a great shipwreck made of solid oak. Large bronze canons lie strewn all around the wreck site.

After many years of searching a team of divers found what appeared to be the legendary Swedish warship Mars, which was wrecked in a battle with the Danish–Lübeck fleet in 1564.

Mars was one of the biggest ships of its era with 107 canons and a crew of 800 men. She was bigger and had more canons than the Swedish warship which sank in Stockholm harbour 1628.

The battle between the Swedish and the Danish-Lübeck fleets off the northern tip of Öland went on for two days, ending with defeat for the Swedes. It is said the Mars lost its capacity to navigate. The Danish-Lübeck fleet then surrounded the Mars, seeing their opportunity to capture her. The Swedes, led by the legendary Admiral Jakob Bagge, offered strong resistance. However the Mars caught fire and exploded. The ship sank and has remained a time capsule, undisturbed for 447 year.

The County Administrative Board of Kalmar has placed a moratorium on diving, fishing and anchoring at the site.