Six people who were aboard a commercial charter vessel that sank Sunday near Richmond remain missing.

RCMP say despite extensive multi-agency search efforts, four men and two women remain unaccounted for and are presumed drowned.

The search has been suspended, and efforts have now shifted to recovery.

The RCMP Underwater Recovery Team will be in the area to locate the capsized vessel using sonar.

Their assessment of the conditions will determine whether a dive operation is feasible, or whether alternate resources, such as a remotely operated vehicle may be required.

The vessel is believed to have sunk in very deep waters.

The investigation remains ongoing to determine the cause of the sinking and to confirm the identities of the six missing individuals.

A 26-year-old man and a 33-year-old woman have since been discharged from hospital. As of yesterday, a 33-year-old man and a 28-year-old woman remain in critical condition.

BC RCMP are working closely with Transport Canada, the Transportation Safety Board and other partner agencies to support the investigation and coordinate next steps.