December 21, 1872

Challenger expedition

HMS Challenger leaves Portsmouth on its scientific expedition

Fifteen of Challenger's seventeen guns had been taken out to make room for laboratories, specimen storage and dredging gear.

Out of Portsmouth before noon

Shortly before noon on 21 December 1872, HMS Challenger steamed out of Portsmouth Harbour to begin its global scientific voyage. Only a small crowd watched it go.

Captain George S. Nares commanded the ship, while Professor Charles Wyville Thomson directed the civilian scientific staff — six people including Thomson himself and the artist-secretary John James Wild, aboard with roughly 250 sailors.

Before the English coast disappeared that evening, the ship met heavy seas and headwinds that continued for several days.

A warship rebuilt for science

A six-month refit at Sheerness had converted the corvette, fitting laboratories, scientific cabins, sounding and dredging equipment and specimen storage. Fifteen of its seventeen guns came out, leaving two.

Thomson was still Professor Thomson when the ship sailed; he was knighted only after the voyage ended in 1876.

What the date marks

Some chronologies mention an earlier departure from Sheerness on 7 December. That was a transfer and preparation leg; 21 December was the departure from Portsmouth for the global expedition.

Descriptions of a four-year expedition are conventional rounding. Challenger returned to Spithead on 24 May 1876, after roughly three years and five months.

The soundings, species descriptions and volumes of reports that made the voyage famous all belong to later stages of it.

Sources

Researched 24 Aug 2026 8 sources not yet audited

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What the sources leave uncertain

The Portsmouth departure date is firmly supported by institutional sources and a participant’s account.
Descriptions of a “four-year expedition” are conventional rounding. Challenger returned to Spithead on May 24, 1876, after roughly three years and five months.
Some chronologies mention the earlier departure from Sheerness on December 7. That was a transfer and preparation leg; December 21 was the departure from Portsmouth for the global expedition.