Thomas Jefferson believed that closeness to the land is essential to virtuous citizenry. For those who share in this sentiment, there are thousands of ways to get involved, even in the lap of luxury. Of course, resorts, cruises and safari camps have been teaming up with leading conservation groups for years — but only a few allow guests to roll up their sleeves and get involved in the action. The following properties go beyond monetary donations and educational lectures, offering rare opportunities to get close to the land — and the sea — and truly make a difference.