Sikuijivitteq (Danish: Mogens Heinesen Fjord), also known as Kangerdlugsuatsiak, is a fjord of the King Frederick VI Coast in the Kujalleq municipality, southeastern Greenland. The name 'Mogens Heinesen' is based on Magnus Heinason, a 16th-century Faroese naval hero.

Sikuijivitteq is located south of Timmiarmiut Fjord (Timmiarmiit Kangertivat); to the east it opens into the North Atlantic Ocean. Ikermiit Island is located off the fjord's mouth.

There are high mountains rising on both sides of the fjord, becoming especially craggy towards the inner side. One of the most impressive is a dark pyramidal peak in the nunatak at the head of the fjord rising steeply to a height of 1,884 m (6,181 ft) on the southern side above the glacier at 62°30′57″N 43°20′44″W / 62.51583°N 43.34556°W / 62.51583; -43.34556.

6 km to the east in the same nunatak there is a steep mountain with multiple peaks rising to a height of 1,894 m (6,214 ft) at 62°31′20″N 43°13′5″W / 62.52222°N 43.21806°W / 62.52222; -43.21806 and at the eastern end there is a massive summit rising to a height of 1,945 m (6,381 ft) above the confluence of the glaciers at 62°31′18″N 43°7′2″W / 62.52167°N 43.11722°W / 62.52167; -43.11722, but the highest is a 2,069 m (6,788 ft) glacier-topped mountain located to the west at 62°32′37″N 43°23′33″W / 62.54361°N 43.39250°W / 62.54361; -43.39250.

• List of fjords of Greenland

• Greenland Pilot - Danish Geodata Agency
• Field relationship of high-grade Neo- to Mesoarchaean rocks of South-East Greenland: Tectonometamorphic and magmatic evolution