They mapped one, "possibly two," axial basins with a depth of 10,915 metres (35,810 ft) ±20 m (66 ft).[37][38] Five dredges were hauled 27–31 March, all into or slightly north of the deepest depths of the western basin. Fisher noted that this survey of the Challenger Deep (western basin) had "...provided nothing to support and much to refute recent claims of depths there greater than 10,915 metres (35,810 ft) ±20 m (66 ft)."[39] While Fisher missed the eastern basin of the Challenger Deep (for the third time), he did report a deep depression about 150 nautical miles east of the western basin. The 25 March dredge haul at 12°03.72′N 142°33.42′E﻿ / ﻿12.06200°N 142.55700°E﻿ / 12.06200; 142.55700 encountered 10,015 metres (32,858 ft), which pre-shadowed by 22 years the discovery of HMRG Deep/Sirena Deep in 1997.[40] The deepest waters of the HMRG Deep/Serina Deep at 10,714 metres (35,151 ft) ±20 m (66 ft) are centered at/near 12°03.94′N 142°34.866′E﻿ / ﻿12.06567°N 142.581100°E﻿ / 12.06567; 142.581100, approximately 2.65 km from Fisher's 25 March 1975 10,015 metres (32,858 ft) dredge haul.