Entitled 'In Remembrance 2', the video show Al-Shabaab coldly executing civilians with machine guns before leaving the bodies to rot on the beach.
The chilling video is the second part of a two episode series by Al-Shabaab's main media branch, al-Kataib Foundation.
The horrific scenes show half a dozen fully clothed civilians being forced into the sea, somewhere on the Somali coast.
Al-Shabaab gunmen, armed with machine guns proceed to callously gun down the prisoners in the sea.
Videoed from the beach, sporadic gunshot is shown hitting the exposed heads of the struggling victims.
The water is shown splashing as the hail of gunfire continues from the beach.
Graphic closeup footage of the dead bodies are shown, floating fully clothed in the water. The lifeless bodies appear to be left unburied, with footage later showing one of the corpses rotting on the sand.
Other scenes show a group of six unarmed young Somali men being led out of a small prison room.
Dressed in brightly coloured t-shirts and patterned trousers, the innocent men are forced to form a human chain, holding the waist of the man in front of them.
As they walk past, several of the victims stare sorrowfully into the camera, whilst the others look down at their feet.
Several militants, armed with AK 47s can be seen standing guard, watching to make sure the prisoners do not try to escape.
Forced to sit on the sandy beach, crude blindfolds constructed out of their own shirts are applied to the eyes of the prisoners.
The men are then forced to kneel near the water's edge. Militants coldly execute the victims with a volley of heavy machine gun fire.
The bodies are shown falling into the sea as the terrorists move on to their next victims.
Using a mixture of archive footage from 2009 and film of recent atrocities, the video embodies the brutal extremist approach being carried out by al-Shabaab in Somalia, Mail Online reports.
The video comes after reports that piracy is making a comeback off the coast of Somalia, following the rise of illegal fishing vessels.