Sand Martin (Riparia riparia)
While spending some time with my friends on a beach of Islay in Scotland, I notice "swallow-looking" birds flying nearby. They were Sand Martins (Riparia riparia)! I sat on the sand and stayed far enough to not disturb them. I had the chance to see them going in and out of their nests located at the end of tunnels they made in the sandy cliff. A great moment!