I may add her commander's name: Chrisan K. Buguraev

more exact location: between Swartklubben – Arholma

and some details on the event (internet find):
"Som" repeatedly left on patrol at dawn, returned to base at dusk. On May 10, 1916 at 4 o'clock in the morning "Som" which was patrolling in the area of Olandsgaf, and was lost in an underwater collision with the Swedish steamship "Ingermanland". As the captain of a steamship has testified, he noticed a periscope, towering 1 m above the water, at a distance of 150 m. The boat went by on a parallel course, and then turned toward the steamship. Having decided, that it wanted to examine them, the captain stopped the ship. The periscope suddenly disappeared under water, and the boat struck the steamship below the waterline. The submarine was not seen again. In addition to the submarine, her crew - 2 officers and 16 bottom grades were lost.


Oliver