I don't have see-thro' trunks, of any make, but I do have tan-thro' ones, made and sold by Kiniki. They are made from a very fine mesh, which with the dark colour scheme makes them opaque to view while letting the UV in.
I used to have a pair of yellow Speedos (genuine Speedo brand too) that, despite a double thickness panel at the front, were completely sheer when wet.
@voodoo1970 on my Speedos, I always cut out the inner lining in front right away. I added some elastic to the strip of fabric I cut out and made a g string that was very revealing.
[To Dunpender] See-through unpleasant? Well, living near a seaside resort, I can assure you that translucent trunks are not necessary to show that a good many, of both sexes, would find the fuller cut swimming attire the more flattering!
I had a light blue small speedo-like swim suit for awile. I became pretty see thru when wet. You could see the outline of me penis pretty good and it rode up my ass. Got some smiles when I wore it to the non nude beach. One guy asked me where I got it. He wanted one too.