摘要:Marudu Bay is the largest bay in Malaysia where the opening of the bay mouth is about 34 km in width, and the bay territorial water area is estimated to be around 900 km2 while the digitized shoreline length measured about 246 km. The bay experiences mixed tidal forces from two (2) seas i.e. the South China Sea on the western region and the Sulu Sea on the eastern side. The geo-morphological features inside the bay is dynamically formed where sandy beaches dominated the foreshore of the bay mouth and muddy shores with escalating mangroves colonies the inner part of the bay. The dominant hydrodynamic forces acting on Marudu Bay is Northeast Monsoon (NEM) where it carries most rain from November until March every year. During Southwest monsoon, it carries drier air that flown through the bay. In this study primary physical marine data was collected inside Marudu Bay in order to understand the hydrodynamic condition inside the bay during NEM period. Since this measurement is the first primary record of physical parameters monitoring effort inside Marudu Bay to date, this finding will astonishingly become an important reference in understanding the dynamic of physical forces in relation with the ecosystem functions and the prominent role of the bay towards the socio – economic stability shared by the three (3) district around the bay, i.e. Kota Marudu, Kudat and Pitas.