Piracy may be a topic of schoolboy adventure stories, but it’s still a dangerous and costly problem for merchant shipping and tourism in some parts of the world. In the pirate-ridden waters of the Indian Ocean, satellites show that environmental conditions have limited recent pirate activity.

Attacks and hijackings of ships by Somali pirates in waters off the Horn of Africa have sharply increased in recent years, and show no sign of waning.

Somali pirates account for over half of attacks worldwide. But while the number of attacks per year continues to increase, 2011 saw a 40% drop in ‘successful’ attacks - or hijackings - compared to the previous year.