27 gripping documentaries that are all essential viewing

SeaWorld announced changes this week to the treatment of orcas at their theme parks, a move influenced by the 2013 documentary Blackfish which explored the risks and ethical implications of keeping killer whales in captivity.

The decision is testimony to how powerful documentaries can effect change - and with that in mind we've rounded up 27 of the most groundbreaking films released in the last few years.

Block book three days off work to get through all of them. We dare you.