Seeking Advice Nikon

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Im new here.Im fairly new to photography,using dslrs I do fly drones and have done for some time.
I have a Nikon D5500 with a shutter count of 4000. Im happy with the camera but concentrating on Seascapes photography.My main concern is the lack of weather proofing.I do have a think tank cover.
I have been looking at the Nikon D810 and was wondering if its worth changing to this body?Also,would the lenses i have for the 5500 fit the 810?
All Nikkor F-mount will fit the D810. If you have 'DX' AF-S lenses they will work in crop-mode only.

Sea salt will kill all cameras eventually and you'll need a cover for a weather proof camera as well. Consider a D500, unless you have Full-frame lenses the D810 will be a good choice. But you will need 'sealed' lenses as the main vulnerability is the bayonet mount.