Give it up for Common Soles, a for-profit business with a well-developed conscience. CS acquires their products from fair-wage and eco-sensitive manufacturers and gives a portion of the proceeds of each sale to support health and education initiatives in needy communities.
CS sells flip flops, and we test walked the Aiman, which uses natural jute plant fiber in the main strap and sole. Jute is a highly sustainable plant that grows mainly from rain water without the need for excessive watering or pesticides. The hand-crafted sandal is very comfortable and provides decent arch support. The sole is tough and grippy for walking around in your travel companion's stomach contents because, well, she can't handle a pitching, overloaded ferry in the middle of the night.
There are plenty of flip flops out there mass produced in ways that harm pretty much everyone involved except the factory owners, so do us all a favor and keep businesses like Common Soles in mind.