Method of providing an electronic map for a marine vessel

A method of providing an electronic map for operating a marine vessel (), the method comprising the steps of: providing () map data, dividing () the map data into a first cell and a second cell () defining a fixed geographical area of the map data, receiving () a first measurement from a first sensor of the marine vessel, where the first measurement comprises a first sensor parameter representing a measurement relating to the geographical area of the first cell and/or the second cell, determining () a risk assessment of the first sensor parameter, assigning () a first risk parameter to the first cell and/or the second cell, operating () the marine vessel based on the first risk parameter of the first cell and/or the second cell.