Dad and Daughter fishing on Lake Michigan find 1871 SHIPRWECK after thinking their sonar was picking up an octopus

A father and daughter mistakenly discovered what is likely to be a shipwreck from 1871 while fishing on Lake Michigan. 

Tim Wollak and six-year-old Henley, from Peshtigo in Wisconsin, were in Green Bay near Green Island in August when their sonar picked up something she thought was an octopus, according to WLUK-TV. 

Wollak shared the photos on Facebook believing it was a sunken vessel and it eventually captured the attention of the Wisconsin Historical Society.

It confirmed the object was the wreck of a three-masted wooden sailing ship under eight to 10 feet of water on Monday after an underwater remote vehicle examined the site on December 4. 

Archeologists believe the ship is the 122-foot-long George L. Newman which sunk during the deadly Peshtigo Fire that killed up to 1,500 people 152 years ago. 

'I was surprised I had never seen it before because it's in an area where people regularly go,' Wollak said. 

The Wisconsin Historical Society shared an update on Facebook to say it had investigated the area and confirmed the discovery was a shipwreck. 

'Although the identity of the wreck has yet been confirmed, the location and current available data fits with that of the barkentine George L. Newman,' it wrote. 

'On the evening of October 8, 1871, the barkentine was sailing through the thick smoke from the Great Peshtigo Fire – the deadliest fire in U.S. history – with a cargo of lumber from Little Suamico when it grounded on the southeast point of Green Island.'

The crew on board the ship were saved by the keeper of the lighthouse and they stayed on Green Island for a week. 

They tried to salvage what they could before the vessel was abandoned, covered with sand and forgotten about. 

'It was actually built in 1855, so it's a pretty significant shipwreck, pretty old for Wisconsin shipwrecks anyways,' Tamara Thomsen, a maritime archaeologist for the Wisconsin Historical Society said. 

'To have it tied to the Peshtigo Fire, it makes it even more special.' 

There are plans to survey the wreck again next spring and the historical society could push for the site to be listed on the National Register of Historic Places. 

'I don't know how we top it,' Wollak said. 'I told her [Henley] I'm pretty sure there's no one else in her school that has ever found a shipwreck that nobody had recorded before.

'I guess we'll just have to fish more and see if we can find more shipwrecks.'

The Peshtigo Fire has been ranked as the deadliest forest fire in US history.

Railroad workers clearing land for tracks started a bushfire which rapidly engulfed up to 1.5 million acres of land, survivors claimed.  

It set fire to parts of Door and Kewaunee counties and consumed Peshtigo within an hour, according to the National Weather Service's website. 

The discovery of the shipwreck comes three months after a schooner which sank in Lake Michigan in 1881 was discovered with the crew's possessions still onboard close to the Wisconsin coastline.  

It was hailed as a 'remarkable discovery' by historians. 

There is estimated to have been more than 6,000 ships which sunk in the Great Lakes since the 1600s.