Mareas or Mareis: How To spell?

The word Mareas is misspelled against Mareis, a noun meaning "A Marsh."

Word contains consecutive vowels 'EI' in between alphabets mar & s is misspelled as 'EA'
Wrong Spelling:  mar-ea-s 
Correct Spelling:  mar-ei-s 
Explore spell check of Mareis to spell without errors.