More than a third of children left primary school this year without learning basic swimming skills which could save their lives, a TES survey reveals.
But children in Wales get more pool-time than their contemporaries across the border, and a chart-topping 96 per cent meet challenges to do with speed, distance and survival skills. They also benefit from free use of public pools during the summer holidays, funded by the Assembly government.
Across England and Wales, though, rising costs, pool closures and pressure on curriculum time have combined to make it increasingly difficult for many primaries to teach swimming effectively, the survey shows.
A headteacher in Gwent, who wished to remain anonymous, said: "We have been able to provide this opportunity for the past 20-plus years because there has been a swimming pool nearby.
"This has now closed and we will no longer be able to offer this provision due to transport costs."
A Cardiff primary school said it was paying pound;100 a day for transport - for a mile-long trip to the nearest leisure centre.
But the head of a small primary in rural Powys said the whole school was able to travel in one bus, "keeping costs as low as possible", despite the 10-mile trip to the nearest pool.
The survey of 224 primary and junior schools in England and Wales found no overall improvement in pupils' swimming skills in the past three years, despite promises of action from ministers.
A similar survey carried out by The TES in 2003 found an average of three out of 10 pupils had failed to master personal survival skills, such as floating. This has risen to 35 per cent this year, suggesting that every year 200,000 pupils miss out on skills that could save their lives.
Drowning is one of the most common causes of accidental death among children, with about 50 fatalities each year.
The survey comes amid government concerns about obesity after ministers in London admitted a third of adults are expected to be obese by 2010.
Swimming is the second most popular participation sport in the UK after walking.
In Wales, swimming is a requirement at key stage 2 as part of the national curriculum programme for PE. It is optional for children in other key stages.
Pupils should be taught to develop confidence in the water, how to rest and float, to develop different strokes, and the principles of water safety and survival. There is no guidance in relation to how far they must be able to swim. But the TES survey found nearly 86 per cent were able to swim 25 metres unaided, compared with an England average of 80 per cent.
An Assembly government spokesperson welcomed the "excellent" results for Wales.
"Swimming is an important skill and that is why it is a compulsory element of PE for all pupils in KS2. Pupils should be taught to develop confidence in the water, to swim unaided and the principles of water safety," he said.
The government's pound;10 million free swimming pilot scheme, started in 2002, will be subject to a full evaluation next year. But provisional figures suggest the average number of swims per summer holiday week by the under-16s has increased from 65,000 to 95,000.
The TES survey reveals big differences in the opportunities on offer to pupils in different parts of the country. While those in Wales averaged 58 minutes swimming a week, the English average was 49 - and 36 minutes in London.
And the proportion of children leaving primary school unable to swim 25 metres unaided has risen from a sixth to one in five since 2003. It suggests the Westminster government's school swimming charter, launched in January 2004, has done little to improve the skills of primary pupils.