Petroleum and coal formation
Coal, oil and gas can be found anywhere on Earth: on land and on sea.

The Japanese once mined coal from beneath the sea floor, using Hashima Island as the base of operations. The island is only 6.3 ha in size.

The British also mined coal from under the sea, in the north east of England.

As for oil, the following picture from USGS shows the current oil-prone petroleum basins in the world, outside of the USA.



The following oil basins are all on land:


Russia
Arabia, Kuwait, Iraq and north Africa
China
Eastern Europe
The Canadian oil sands and other plays in the province of Alberta, Canada
Colombia
The oil fields of east Texas, USA
The former oil fields in Pennsylvania


When oil &amp; coal deposits formed they each had different mechanisms of formation. Coal is derived of plant material that once lived on land, died, formed peat, which then got buried.

Oil however, owes its origins to algae &amp; plankton that lived in the oceans. When they died they sank to the bottom of the ocean and deposited in waters with very low, if any oxygen. Eventually, these deposits were covered by sediments. If the deposit was subject to a significant amount of geothermal heating gas deposits formed, otherwise oil deposits formed. Movements of the Earth's crust then repositioned some of the deposits which is why some coal is now under the sea and some oil is now on land.