Just some general knowledge. There is a abandoned building near the Silent Tower, right here
At a first glance there seems to be only three chests inside of it, each behind a staircase leading down till eventually it reaches sea level. What pains me is that i see people who take the three chests and leave, as you can swim below sea level, and it reveals 2 more floors, one with 2 and the other with 5. Making the total chest count 10, which is a big upgrade compared to only 3 chests.