I saw a group of about 18-20 several times on Merriam Bay on June 30th and July 1st.  They were team-fishing some small deepwater baitfish.  It appeared about half the group would dive first, head deep and drive the baitfish towards the surface.  Then the next group would dive to intercept.  Once when I was very close, shortly after the second group dove, I saw tiny baitfish frantically jumping out of the water.  That's what clued me in to their strategy.  The loons basically paid zero attention to me unless I was within 15-20 feet.  Would have been cool to capture on camera if it hadn't been raining.