Duolingo grammar is incorrect. The info read "Es un barco enorme", which means "It is a huge ship". Duolingo did not have the proper word selection. You had "an" not "a", so your choice was to say "It is an huge ship" is incorrect. It should be "It is a huge ship". So, I did not chose the choice of the word "an". You should have accepted my answer. Duo is incorrect.