Scoop up litter from canals. Volunteer on an urban farm. Pedal by bike instead of driving. As a reward for green deeds, visitors to Denmark's capital, Copenhagen, can get perks like free ice cream, glasses of wine and discounted museum entry.

From BBC, it's part of a newly launched initiative called CopenPay, which encourages travellers to think and act a little more sustainably. From art galleries to sports-rental outfits, 24 attractions are taking part in the one-month pilot scheme, which runs until 11 August.

"We want tourism to be a force for positive change and not an environmental burden," explained Rikke Holm Petersen, director of marketing at tourism board Wonderful Copenhagen who are behind the initiative. "When you go travelling, you sometimes forget the good habits you have at home," she added. "We want to inspire a more conscious, sustainable mindset and behaviour amongst travellers."