There is no shore to retreat to in Azure Mare. The tide rises from the bottom row on a fixed clock, and it doesn't recede.
Rising Tide
Rising Tide
The bottom row fills in on a timer whether you clear it or not. Azure Mare is the closest the game gets to a countdown — read the swell before it breaks.
It's the final realm for a reason: every mechanic from the first four realms shows up somewhere in its bosses.