Record #00516Nature archive
On 13 October 1986 in the eastern Weddell Sea, four expedition observers could still see a Secchi disk at 79 m, but it disappeared from view at 80 m, establishing an exceptional seawater visibility measurement.
Current Record
79m
Current record value
The expedition measured unusually clear water in an eastern Weddell Sea coastal polynya. The original paper specifies 14:45 UTC and a position near 71°23.63′ S, 15°02.52′ W.
A roughly 30 cm white Secchi disk is a classic visual method for assessing water transparency. The primary report distinguishes visibility at 79 m from disappearance at 80 m; later studies and record compilations often describe the limiting depth as approximately 80 m.
The record conclusion has sufficient verification support.
Basis: comparison of consistent primary data
Gieskes et al. directly documented visibility at 79 m and disappearance at 80 m; a 2024 academic review and Guinness use 80 m as the limiting depth. The record explicitly measures the deepest confirmed visible level, so the Entry stays at 79 m. Guinness's unrelated metadata of UK and 2004 conflicts with its 1986 Antarctic narrative and is not used for date or location.
Current Entry identifies the current entry in this archive; it does not establish that the record is still held today.
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