As warmer weather returns to London and more people are out enjoying the sunshine, the Met's Marine Policing Unit (MPU) is raising awareness of the dangers of entering the capital's waterways.

Chief Inspector Rob Ranstead, who leads the Met's MPU, said: "We absolutely understand the natural draw of rivers, lakes and open water across the city.

However, we have sadly seen a recent rise in incidents where people have got into difficulty - and very tragically, some have lost their lives.

"So, I want to make a direct appeal to the public: please enjoy London's waterways safely but never underestimate the risks."

He continued: "Open water may appear calm and inviting, but it can be dangerously deceptive.

"Strong currents, sudden drops, hidden hazards, and cold-water shock can affect even the strongest swimmers.

"Once a person is in the Thames, for example, they will almost definitely struggle to keep afloat or in control.

"The river holds currents stronger than any person and moves at extreme speeds.

"The water may look calm, but the tides are extremely strong and fast, able to easily drag someone a mile in just ten minutes."

The Met MPU's "simple but potentially lifesaving" advice is as follows:

• Do not swim in open water unless it is part of a supervised and safe environment.
• Never enter the water under the influence of alcohol or drugs.
• Talk to your children and young people about the risks—many incidents involve teenagers during school breaks or weekends.

Chief Inspector Ranstead added: "Our officers patrol the River Thames and many of London's waterways on a daily basis.

"We see the heartbreak and devastation these preventable tragedies cause – with families changed forever in a matter of seconds.

"Working with partners we are increasing our visibility and delivering water safety education, but we need the help of the public. Please respect the water, look after one another, and think twice before taking unnecessary risks."

On average the Met's MPU is called to over 140 incidents each month on the River Thames.

It works with partner agencies such as the RNLI, HM Coastguard, Port of London Authority, Tidal Thames Water Safety Forum and London Fire Brigade, to help keep the tidal stretch of the Thames safe for Londoners.

• If you find yourself in the water, you should follow the RNLI's 'Float to Live' steps:
• If you fall into water, fight your instinct to thrash around.
• Lean back, extend your arms and legs.
• If you need to, gently move them around to help you float.
• Float until you can control your breathing.
•  Only then, call for help or swim to safety.