My brother in law was working on his boat transferring gasoil from one tank to another but did not realize that his friend has closed off the pipe with a cover. When he realized it it was too late a substantial amount had flown into the salt water in front of his house.

He put dishwashing liquid over it but that did not help. He really wants to clean out the mess so that the gasoil does not start floating to the beaches or other areas.
What can we do?

Thanks so much for your help

How much was actually spilled in gallons?