My memory, which is increasingly faulty these days, includes some singer, somewhere, sometime (I could be more vague), explaining that the "hill and gully" actually referred to crests and dips in ocean waves, being "ridden" in a small boat.

I remember the version by the Tarriers, at least that's what I keep hearing (and will for days now [hill and GUL-LY in bass voice], thanks a lot!).

~;o) - Mary