THE Environment Agency is urging people to be vigilant when playing or relaxing by rivers.

Children can often be attracted to the water's edge during the long, hot summer break, and problems arise when children and adults fail to realise the real dangers concealed in the River Thames.

Almost every summer, this lack of awareness leads to tragedy, the agency said.

Things to be aware of, according to the agency, include the fact the water can be deceptively cold, the speed of the flow is often well above the capabilities of even the strongest swimmers and boats and other moving craft find it very hard to spot swimmers.

Other less obvious considerations are unseen water obstacles which can include submerged landing platforms and discarded articles such as motorcycles, shopping trolleys, washing machines and other hazardous material left by the public.

The depth of the water is often uncertain and water-borne diseases can be found on many stretches of the river.