On my lagoon I used one, mine serves a dual purpose though. It does the obvious of keeping water out and goes the extra mile by keeping my kids out. This one has a lock option too haha. When looking for one make sure it can fit your intended plugs and the exit port goes in the direction you want. Some covers are only weather proof when not in use.
I have actually thought about this for a while.... like y not right just added protection.
Thanks for the tip that some are only waterproof when not in use.
The one draw back possibly with that particular one is it has to expand out with the rubber shroud when in use. There are options out there that stay closed while in use.
I installed this one outside on my back deck. It can be used vertical or horizontal, and both sides have wire outlets.