Answer: tidemark

AnswerCrossword Clue
TIDEMARKSpot showing a flood's highest water
TIDEMARKLine on a seawall
TIDEMARKHigh-water point, usually
TIDEMARKLine on a dock
TIDEMARKShore line
tidemarkmark made to indicate the highest or lowest point of a tide
tidemarkthe point that something or someone has reached, receded below, or risen above
tidemarkmark left by the highest or lowest point of a tide
tidemarka mark showing the highest or lowest points of a tide