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 Crew Neck T-Shirt (Model T40-2)
Type: Polyester Fabric, All-Over Printing                 
Production Time: 5-7 days
 
9.35 Oz. Made from 100% polyester, Lightweight and soft, comfortable and breathable.
Features round collar designed to keep its shape.
Each panel is cut and sewn together to ensure a flawless graphic.
Sizes: S, M, L, XL, 2XL, 3XL, 4XL, 5XL.
Garment Care: Hand wash or machine wash with cold, on gentle, inside-out. Do not bleach.
 
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.