This was a design for the now sadly defunct Skinny Bear tees. All my designs for them took the form of bizarro promo t-shirts that suggest a larger story. The product description read:

A once popular holiday destination, Obsidian Waves Water Park has been owned and operated by the Marsh family since 1937. The Innsmouth landmark is open every year from October to April.

Tees and prints and such are now available here.