Does it mean anything when the spike there goes off the top of the grid. Should it all fit in horizontally and vertically ideally
No. The vertical (Y) axis represents how many pixels are recording that particular part of the histogram. The Y axis has no bearing on exposure.
Example:
Here's a fully grey image filled with grey (128R, 128G, and 128B)
Obviously the Y axis is filled from top to bottom because all the pixels are the same colour. The histogram is a single line because all the colour is the same grey.
Oh... and the spike is dead centre because it's RGB128... exactly in the middle of the 8 bit colourspace (0-255 levels per pixel - you count the zero so 256 discreet levels)
You'll hear people talking of the perfect histogram as a bell curve... just laugh at them... they're idiots. The histogram above is a perfect histogram for that image. I can replicate this in real life as my walls in the digital darkroom are painted 18% grey. (note the image is not rendered as 18% grey, as most camera meters are not actually calibrated for 18% grey any more... close... but not 18)
The histogram is no longer a single spike as there are variations in the grey due to the textured wallpaper, but the majority are still recording a very similar shade of grey, hence still a full deflection on the Y axis and a very narrow range of the histogram being occupied.
This however is a perfect histogram for this shot.
I can stretch it out to fill it and get a "bell curve"....
...but it looks s***!
You don't necessarily need a full histogram if the scene you shot didn't generate one.
There's nothing wrong with the OP's shot, and in my opinion, getting a black will lose the sense of distance, and lose that feeling of a bracing on shore breeze and salt spray, but this of course is subjective.