I must happily acknowledge the influence of ainhoa_v on this design. This layout copies their style quite explicitly, and they were very kind to give permission to use the background (a blend of 2 of their long beach shots with the people removed). 
 
https://www.instagram.com/ainhoa_v/ 
 
Once I had the background and the idea of silhouetted figures spread like a pattern, it was just a matter of finding the right vectors of people on Pixabay and coming up with a way to handle their reflections.
 
InterestPrint® All Over Print Hawaiian Shirt (Model T58) - Lightly Tailored
Type:  95% Polyester, 5% Spandex, All-Over Printing                
 
7.30 Oz. Personalized and stylish.
Made from 95% polyester and 5% spandex, lightweight and comfortable.
Each panel is cut and sewn together to ensure a flawless graphic.
Regular fit with short sleeves. Complete with V-neck and side slits.
Sizes: S, M, L, XL, 2XL. Please calculate your size from the measurement chart below.
Machine wash: cold (max 40℃ or 104℉); non-chlorine; iron with cover; do not tumble dry; hang dry out of direct sunlight.
 
Size charts in inches/cms:
https://www.whythealgarve.com/post/hawaiian-shirt-size-charts-hugepod
 
 
 
 
InterestPrint says: 
We can't guarantee exact placement. There might be slight discrepancies in print placement. 
We allow the color accuracy deviation of the finished product and the mockup image to be within 5%. 
There may be small differences in the design of clothing products, with a deviation of 2-3 cm measured manually during the production process. 
It is impossible to perfectly align patterns or images from front to back for all over print products.