What Nicola Oakley, head at St Peter's Church of England primary school in Leicester, likes about the National Trust's second environmental activity centre at Brancaster, Norfolk, (the other is in Wales) is that "you can combine an outdoor holiday with real education. Lots of places offer canoeing and sailing, but not linked to the curriculum. And the place is so beautiful."
Bronwen Cook, who teaches at St George's middle school in King's Lynn, is impressed by the opportunity to study not just the landscape and wildlife but also the centre's building, a traditional East Anglian flint-faced house built in the late 17th century. "The children were fascinated," she says.
Brancaster Millennium Activity Centre is at the head of a small creek off Brancaster Staithe harbour, 21 miles north of King's Lynn. It is a place of dramatic skies and wide beaches, with miles and miles of mud flats, dotted with boats at low tide. There are both salt and fresh water marshes all around.
One of Brancaster's volunteer workers says: "The best thing is the way the light plays on the marsh. It makes the reeds look golden. Children and adults can be inspired by the beauty, they can stop and look and listen to the birds. I like seeing children lying on the ground watching the oyster-catchers through binoculars.
"To walk out of the door, hear the sound of the boats clunking together, see the birds - it's a marvellous experience.
"The local people tell stories of things that happened here as well, like smuggling."
It has taken nearly 15 years and pound;1 million from various sources for the National Trust to transform the 17th-century Dial House - so named because of the sundial on it - from a group of semi-derelict farm buildings to residential premises. Now you can have an adventure holiday and study the conservation and ecology of the coastal landscape here.
"Everything we do is related to the curriculum," says Sue Falch-Lovesey, the centre manager. "The aim is for fun, first-hand experience and discovery."
Externally, the house looks much as it must have done when it was first built. Although it has been extensively refurbished, it incorporates many ecological design principles. Engineers restoring the interior were required to use wood from managed forests and metals such as steel and copper.
The water is supplied by mean-use taps (an irritation) and nearly half of the power used comes from natural sources. Some is supplied by solar energy panels and a wind turbine, and heat is drawn from the North Sea mud flats through a mile of coiled plastic pipe.
The mud is studied scientifically, but it pleases younger visitors in various ways, and features in many of the reports they write when they return to school. "I loved it when I fell in the mud while I was sailing" is typical.
They can also get muddy walking, orienteering or riding the 38 mountain bikes of varous sizes, one of which even has a solar power supply to help going uphill.
The children are taught how to check bicycle brakes, wheels and steering. "I liked biking to Titchwell for three miles and looking at all the birds," wrote one.
"I like solving clues at orienteering to find out the bird," wrote a seven-year-old, while a 10-year-old said: "I liked doing the sailing when I got soaking wet."
The opportunities for bird-watching and studying the fresh and salt-water marshes are enthusiastically taken and on guided walks plants and insects are identified and recorded. Children are shown how to avoid walking on the same tracks and damaging the marshes and woodlands.
Nicola Oakley was pleased particularly with the equipment. "We cycled to the bird sanctuary and the children loved the fact that they each had a pair of binoculars," she says. "It meant they could participate from the beginning.
"The level of participation in the orienteering was just as good," she adds. "The group shared compasses one between two, and the pairs went off independently for 20 minutes. Of course, there were adults all around the area they were working in, but the children couldn't see them, so they really felt as though they were working on their own."
Since the centre opened last May a predictable pattern of use has developed. Local schools come for the day and pack in as much as possible. Groups from further away stay for four or five days and take the activities at a more leisurely pace. The facilities include simple accommodation in rooms with names such as Dormouse's Nest.
Nicola Oakley thinks the residential experience is important. "They're learning to get on with one another," she says.
Children also discover new preferences: apparently they all love cooked breakfasts.
During a five-day stay, a key stage 2 group could sail, cycle, do some orienteering and bird-watching, investigate the salt marshes, consider a computer graphic of the heating system for Dial House and go on an historic reconstruction visit to Blickling Hall or Holkham Hall.
At present there is an emphasis on KS2, although KS3 and KS4 can also be provided for, and A-level students are taught in the field by their own teachers.
As always with such trips, the social experience and the adventure contain as much educational value as the curriculum content. Amazingly, some of the Leicester children had never before seen the sea.
Brancaster Millennium Activity Centre, The Dial House, Brancaster Staithe, King's Lynn, PE31 8BW. Tel: 01485 210719. Cost is pound;105 to pound;130 (depending on the month) for each child for a five-day stay. Questions of staff qualifications and safety are answered on the literature. For information and a preliminary visit, contact Susan Falch-Lovesey