Banc du Geyser (also Banc du Geysir) is a mostly submerged reef in the Mozambique Channel's northeastern part, 125 km (78 mi) northeast from Mayotte, 112 km (70 mi) southwest of the Glorioso Islands, and 200 km (124 mi) off the northwestern coast of Madagascar. The Geysir Reef was first known by Arab sailors around the year 700, and was shown on some navigation-charts dated around 800. Around 1650 the reef was shown on Spanish maps as Arecife de Santo Antonio. The current name was given on 23 December 1678, when the British vessel Geysir ran on the reef.