On the eco trail, from Madagascar to New York

Green-minded travellers are set to enjoy some of the best holidays on offer this year. Sarah Barrell picks her favourites

Recent statistics may have warned of "green fatigue" as this country's populace grows confused about carbon footprints and weary of natural disasters, but environmentally aware projects abound in the world of travel.

And far from being hair-shirt, they make for some of the highlights of holidaying in 2008. From expanding cycle networks to new national parks, the following ideas reveal that there's a growing choice of ideas for the green-minded traveller.

The High Line, the eagerly awaited "floating" park in Manhattan, is slated for opening this autumn. Like the Promenade Plantée in Paris, the High Line (thehighline.org) follows the path of a disused elevated railway that once carried dock freight above the streets of Chelsea. This 1.5- mile-long park is backed by all manner of celebrities, and its unveiling promises to be a buzzy affair. But beyond that it promises to bring an innovative green space to the post-industrial Chelsea landscape.

This year will be a busy one for Sustrans (0845 113 0065, sustransconnect2.org.uk). The sustainable transport charity has just won – by public vote, – the Big Lottery Fund prize of £50m for its scheme Connect2 to restore paths, bridges and tunnels in 79 communities across the country.

One of the first projects, and a good example of the scheme, will take place in the Scottish town of Dumfries. A picture-perfect, defunct railway viaduct spanning the River Nith is being transformed into a traffic-free pedestrian/cycle route, helping to connect communities in the north of the city and provide a direct link to the popular traffic-free Caledonian Path. The route will also include a connection to Dumfries station and the city centre. Once completed, in late summer, the route will form part of National Cycle Network Route Seven, stretching from Carlisle to Inverness.

Camp up a tree but lose none of the facilities available on a fully equipped campsite? If this sounds like your way to go under canvas (or canopy), then try one of the new tree houses being introduced at three Keycamp (0844 406 0319; keycamp.co.uk) sites at Carnac and Dol-de-Bretagne, Brittany, and at Berny Rivière, near Paris.

These thatched houses have been artfully designed around the trunk of the tree and are set about five yards off the ground, accessed by a spiral staircase. Each has one double and four single beds, plus lovely decked terraces. Five nights at La Croix du Vieux Pont for two adults and up to four children costs from £449, including return Dover-Calais ferry.

According to Responsibletravel.com (01273 600030) the leading directory for specialist eco holidays, Madagascar is set to challenge the Galapagos for nature tours, thanks to its abundance of native species and conservation projects.

The company predicts that the trend for "authentic" holiday experiences will increase, and reports a sharp rise in bookings to Central and South America, with Madagascar to follow suit.

Responsibletravel. com is working with NGO Conservation International on projects in Madagascar and participates in community-based tourism that works in partnership with local people to protect their culture and environment. The destination may be exotic but it's far from "difficult" and is a perfect choice for families.

A 13-night small group tour of Madagascar's jungle and marine life costs £1,999 to £2,599 per adult and £1,819 to £2,009 per child (over-fives only).

A love of natural wonders is no new thing to Iceland but the country has added another national park to its number, thus creating Europe's largest. Vatnajokull will cover an eighth of the island and is set up to protect the vast eponymous glacier. The protected area incorporates two existing national parks and will include a glacial lagoon with floating icebergs. There will also be the world's first hydrogen-powered whale-watching ship.

Icelandic buses already run on hydrogen and the island leads the world in hydro and geothermal energy use, but this summer the cruise boat Elding, operated by Reykjavik Whale Watching, will sail out of the capital's harbour powered solely by hydrogen. The design is pollution-free and eradicates vibrations caused by regular engines that might disturb marine life.

For more details contact Icelandic Tourist Board (00 35 45 355 5001; visiticeland.com).

Not sure if you've got what it takes to be more than an armchair conservationist? Why not try a new taster weekend from Biosphere Expeditions (0870 4460801, biosphere-expeditions.org), the non-profit group that takes volunteers to work on wildlife conservation projects in far-flung places.

New to its programme, these short breaks in the UK and Germany teach participants the skills needed in the field when assisting scientists with wildlife research and conservation.

Learn to work with GPS and compass, read animal tracks, use telemetry equipment and wildlife camera traps while learning about the fauna, flora and conservation work taking place in your chosen national park.

Weekends are held in the Peak District, Norfolk Broads, and New Forest in May and June and cost £195 all-inclusive with one night's accommodation in a four-star hotel.