This picture was taken by Ratan Lal on 15 May 1968. The event took place near Dwaraka, where Krishna lived, which is on the west coast of India, about 325 miles northwest of Bombay. The description of this event is given by N. Kasturi in Sathyam Sivaram Sundaram, Part III, on page 183-184. We paraphrase:

While returning to Jamnagar in the evening, Baba suddenly said, "O, the sea is here!" and the cars stopped. We came upon a wide patch of sandy shore, with a temple on a heap of rocks at one end. Baba walked along the watery edge and sat on the sands at last, as Krishna must have sat some fifty centuries ago.

He heaped the soft sand to the height of a cubit in front of him, putting us all into a state of extreme expectancy. He flattened the heap and, with his finger, drew a three-slanted line, a rough circle on top of it, a small triangle over that, and finally a short line across the circle. "It is ready," he said. Digging his hands deep into the pile, he drew forth a bright golden image of Lord Krishna playing the flute. "You did not get darshan of Krishna in the temple; have it now," he said.