Throughout his career, Rehn was dedicated to perfecting his craft, experimenting with various techniques that showcased his exceptional skill as a painter. His artwork is characterized by its attention to detail and ability to evoke the beauty of the marine world. As president of the Salmagundi Club, Rehn played an integral role in promoting American art and artists, cementing his place as one of the most respected figures in the field.

Rehn's artwork continues to be celebrated for its timeless elegance and masterful execution.