2025 Proclaimed the 'Year of the Octopus' Off Britain's South Coast.

Exceptionally high encounters of a supremely intelligent sea creature over the summer months have prompted the designation of 2025 as the octopus's year in a seasonal assessment of UK coastal waters.

A Confluence of Factors Driving a Surge

A mild winter coupled with an exceptionally warm spring triggered a massive influx of Mediterranean octopuses to take up residence along the southern coastline of England, across the southwestern peninsula.

“The volume of octopuses caught was of the order of about thirteen times what we would normally expect in the waters around Cornwall,” commented a marine conservation officer. “Based on the totals, around 233 thousand octopuses were present in UK waters this year – which is a significant rise from the norm.”

The common octopus is indigenous to British seas but ordinarily in such small numbers it is rarely seen. An explosive growth is attributed to the dual effect of gentle winter conditions and a warm breeding season. Such favorable circumstances meant more larvae, possibly in part fuelled by large numbers of a favored prey species noted in recent years.

A Rare Phenomenon

The last time, such an octopus proliferation comparable was documented in the 1950s, with past documentation indicating the previous major event happened in 1900.

The sheer quantity of octopuses meant they could be readily observed in nearshore environments for the first time in living memory. Diver videos show octopuses being sociable – unlike their typical solitary behavior – and “walking” along the seabed on the tips of their limbs. One creature was even recorded reaching for a diver's camera.

“During a first dive off the Lizard peninsula this year I saw five octopuses,” the officer added. “They are large specimens. We have two species in these waters. One species is rather small, the size of a ball, but these common octopuses can be up to a metre and a half wide.”

Predictions and Marine Joy

If conditions remain mild going into 2026 meant it was possible another surge in 2026, because historically, under these conditions, events have occurred consecutively for two years running.

“However, it is unlikely, from previous blooms, that it will become a permanent fixture,” they cautioned. “Marine life is unpredictable currently so it’s a very uncertain scenario.”

The report also highlighted other “surprises, successes and joyful moments” around the UK coastline, including:

• A record number of grey seals observed in one northern region.
• Record numbers of puffins on an island off Wales.
• A first-ever sighting of the *Capellinia fustifera* nudibranch in a northern county, normally residing farther south.
• A variable blenny discovered off the coast of Sussex for the first time.

A Note of Caution

Not everything was good news, however. “The year was bookended by environmental disasters,” said a head of marine conservation. “A major tanker collision in March and a spill of tonnes of plastic biobeads off the Sussex coast were serious issues. Staff and volunteers are making huge efforts to protect and restore our shorelines.”