The videos and images taken during observations in the deep seas not only show the sights of deep-sea organisms and interesting views of the sea floor that normally cannot be seen, but also on occasion show manmade litter. The type of litter varies widely, with some even found on the deep sea floor far from land. The increase in marine litter, including plastic, has led to concerns about its effects on ecosystems, tourism, and even humans. The worldwide problem of plastic streaming into the ocean is an issue that deserves our urgent attention.

Hydrographic activity, such as publishing nautical charts and providing maritime safety information to mariners, is essential for securing safety in maritime shipping that supports the global economy. In addition, the effective implementation of such efforts in developing countries has been recognized internationally as an important issue. Through a variety of human resource projects, Japan has been making significant contributions to the world's Hydrographic capabilities through international human resource development and the creation of global networks.

In Palau, the non-governmental organization Japan Mine Action Service (JMAS) has been working to dispose of explosive remnants of war (ERW) since 2012. For example, the outsides of many depth charges (weapons for anti-submarine warfare) remaining on the Japanese cargo vessel known as Helmet Wreck have rotted in the 70 years since the war, releasing the poisonous picric acid. As this acid has negative impacts on the water condition in the gulf, JMAS took efforts to prevent this up until 2015. Currently, the organization deals with monitoring and disposing ERW found on sunken ships and in shallow waters and in securing safety in the oceans.
Selected Papers No.24