Norway
Narrow tidal strait near Bodø with one of the world's strongest tidal currents, designated a marine protected area, offering brief-window drift diving among dense kelp and anemone walls.
Saltstraumen is a narrow strait about 10 km southeast of Bodø, where up to 400 million cubic metres of water pass through a roughly 3 km channel every six hours, with current peaks around 7-8 knots. Designated a Marine Protected Area, diving is only possible in a short slack-water window around each tide change with a certified local guide. National Geographic has listed it among its top diving destinations. Source: Wikipedia (Saltstraumen), Visit Bodø, PADI.