TIDEMARKS is a playable word

tidemark Scrabble® Dictionary

noun
pl. tidemarks
a mark showing the highest or lowest point of a tide
641 Playable Words can be made from "TIDEMARKS"
   2-Letter Words (27 found)
   3-Letter Words (90 found)
   8-Letter Words (4 found)
   9-Letter Words (1 found)