I'm in the process of returning this item that I purchased. Opened it & immediately ascertained this shirt was not fitting me BUT one of the little people that I watch on TV.
I ordered this shirt for my son and ordered up one size (better too large than too small). However, it was very tight on him. I think the sizing on this item needs to be adjusted.
This shirt is tight-fitting (like the other reviews state), which works well for what it is designed to do- protect you while in the water. If you want it for this purpose, it is great and the sizing is appropriate. I am 6'4" and 190 lbs- I wear a large LLBean t-shirt and I wear a large in this.
If you don't want it for this purpose and don't want a tight-fitting shirt, you will never be happy with the sizing no matter how large you get it.
I'm a size 40 M/L, we ordered the L. It was painfully tight. The same size as my 8 year old daughter's childrens L T-shirts. I'm doubtful that the XXL will fit based on other reviews. This one needs to go back to the drawing board.