The periodic fluctuation of the sea is called tides.
That would be TIDE.
The rise and fall in sea level caused by gravity is called a tidal cycle. Tides are caused by the gravitational forces of the moon and the sun acting on the Earth's oceans.
tide
The two homophones are "tied" (done with shoelaces) and "tide" (rise and fall of the sea).
The rise and fall is the tides.
The vertical movement of the surface of a body of water, such as the ocean, is called "sea level rise" or "sea level fall." Sea level rise can be caused by factors like melting ice caps and glaciers, while sea level fall can occur due to factors like global cooling and the transfer of water to ice storage on land.
The tide
It is aclled an high tide
Tides
If you use Tide with a capital T it may appear that you are infringing upon the trademark of Tide detergent, but if you use tide with a lower case t, it's just a word, part of the English language, which refers to the rise and fall of sea level due to the influence of lunar gravity.
When the water of the ocean is at a higher level than its average, this is referred to as sea level rise.