RE:Exxon's Discoverieshttps://oilnow.gy/discoveries/guyana-history-with-oil-dates-back-centuries/
Growing up in the '70's it was rumoured that there is a lot of oil below the seabed but it was not economically worth the effort to get to the oil. I don't know if that was true or false but now it seems economically viable, especially with modern technology and all.