Oceanographic conditions, mainly wave and sea water current, in the study sites were influenced by wet monsoon period, i.e. from November to April. During the wet monsoon (wet season) the wind is characterized very strong, which blows from North-west to South-east or from South-west to North-east, with velocity ranges 7–20 knot (≈ 13–37 km/hour). The strongest wind usually occurs in around December–February, with velocity is about 45 km/hour. During this season the sea wave may very high, sometime > 2 m especially during December–February. While the east monsoon (dry season), it usually occur in period of May to October, with wind velocity is relatively calm, that is about 7- 15 knot (≈ 13–28 km/hour). The sea wave was not very high reaching only around 0.8 m. The sea water current in Riau islands follows the current pattern in Malacca strait. It is depends on the different between seawater level in northern part of Andaman Sea and southern part of Malacca Strait. Since seawater level in Pacific Ocean is always higher than in Indian Oceans, the seawater level in South China Sea is also higher than in Andaman Sea through out the year resulted in Malacca Strait there is a current, which flow to Northwest direction through out the year. In November to April, during the Northeast monsoon, Andaman Sea's current goes to the north. Therefore, majority of water masses are transported to the north. Consequent of this, during these months, Andaman Sea's water masses will be empty, and sea water level will be low or the different from South China Sea's sea water level will be higher. This sea water level reaches to maximum in February to March, while the different of sea water level between Northern and southern parts of Strait is about 50 cm, which resulted current velocity is about 12 cm/sec to Northwest.