The Bluefin-21 is a highly modular autonomous underwater vehicle able to carry multiple sensors and payloads at once. It boasts a high energy capacity that enables extended operations even at the greatest depths. The Bluefin-21 has immense capability but is also flexible enough to operate from various ships of opportunity worldwide. This is the UAV being used to search for the Malaysian Airliner in the Indian Ocean. The Bluefin 21 has a built-in safety feature which forces it to return to the surface once its limit is exceeded.