Two U.S. Navy SEALs drowned as they tried to climb aboard a ship carrying illicit Iranian-made weapons to Yemen because of glaring training failures and a lack of understanding about what to do after falling into deep, turbulent waters, according to a military investigation into the January deaths.

The review concluded that the drownings of Chief Special Warfare Operator Christopher J. Chambers and Navy Special Warfare Operator 1st Class Nathan Gage Ingram could have been prevented. But both sank quickly in the high seas off the coast of Somalia, weighed down by heavy equipment they were carrying and not knowing or disregarding concerns that their flotation devices could not compensate for the additional weight. Both were lost at sea.

The highly critical and heavily redacted report — written by a Navy officer from outside Naval Special Warfare Command, which oversees the SEALs — concluded there were “deficiencies, gaps and inconsistencies” in training, policies, tactics and procedures as well as “conflicting guidance” on when and how to use emergency flotation devices and extra buoyancy material that could have kept them alive.