View the original post on Musing.io
First thing that needs to be mentioned is that lightening does strike the seas and oceans but it does so with a lot less frequency than it does land. When the lightening does strikes the sea or a ocean surface two things will happen simultaneously.
The first will be that the electron discharge would appear to spread away (remember that electrons don't travel the whole way, but their simultaneous movement carries a net flow of charge). This would appear in the form of a current that would spread in the sea.
Second thing that would happen is that the surface of the water would be the area on which most of the current flows through. This means that the electrical flow of the discharge would travel much more strongly on the surface of the water than it does towards the depth of the sea.
If there are any creatures around the area they would experience the shock of the strike much more severely if they are closer to the initial strike zone. The amount of shock they would feel is dependent on two things - first the mineral (ionic) content of the water and secondly the ionic content of their own body.
It is said that creatures near the surface experience more hurt than the creatures under the surface (this might be true, since we know that most of the current flows on the surface of the sea).
The above is an image by NSSTC Lightning Team. NASA's Lightning Imaging Sensor collected this data between 1995 and 2002, for their tropical rainfall measuring mission. It shows that most lightening strikes are concentrated on land.
Hopefully we don't have to worry much about a lightening strike on water. We have more reports of shark attacks, than lightening striking humans at sea. But remember that when this does happen, your best chance is to find an insulated area on the beach or a boat.