I think the Blue Seas offerings are the same or at least similar to the Hella/DIN ones I illustrated, the sockets of which have a waterproof cap when not in use. There is a matching adaptable plug available that allows use of the awful cigar lighter sockets as well, shown below.
![[Linked Image]](https://16.cdn.ekm.net/ekmps/shops/altecshop/images/12mm-cigar-lighter-plug-to-fit-hella-bosch-socket-din-iso-4165-alt-p721-303-p.jpg)