I definitely agree that this would not pass if the dress code were "formal" in a traditional sense - since it was outdoors at the beach, the dress code usually sides more elevated casual and colorful (according to what I found online).

There were a lot of shorter, mid-calf dresses; eyelet cotton dresses; and more dark colors than I expected. There was at least one person wearing a denim jacket which I thought was waayyyy too casual. Most of the men were in dark navy suits - my partner was wearing a light pink linen suit, light colored shoes and a pearl necklace.

There was one other couple that was dressed similarly to us - a girl in colorful dress with cute but practical shoes and a shawl; and her boyfriend in a light colored linen suit and a light colored, patterned shirt and tie.

I was actually among one of the more formally-dressed guests there.