Tuvalu prime minister Feleti Teo has called for an international treaty on sea level rise at the UN Oceans Conference in France.
Speaking to delegates in Nice, Teo said the ocean is critical to his country's economy, culture and survival.
He said he supports the UN Secretary-General's call for all nations to deliver on the 1.5 degrees Celsius promise in order to halt the rate of sea level rise.
"In that regard, Tuvalu calls for the development of an international treaty on sea level rise, to enshrine the legal rights of affected states and people, including the principles of statehood continuity and the permanency of maritime boundary," he said.
"For Tuvalu, building the resilience and adaptability of our coastlines against the impact of sea level rise is our top adaptation program."
Solomon Islands prime minister Jeremiah Manele used his speech to condemn the pursuit of deep sea mining in the Pacific.
Addressing delegates in Nice, Manele said his country has placed a moratorium on deep sea prospecting and mining.
He said the world's oceans face three planetary crises: biodiversity loss, pollution and climate change.
"Despite this, some are pursuing deep sea mining with minimal regard for scientific understanding, environmental risks and global consensus," he said.
He said the UN Sustainable Development Goal 14 - to conserve and sustainably use oceans, seas and marine resources - is off track and underfunded.
"We must move beyond rhetoric to concrete actions that matches the scale and urgency to address today's crisis.
"We must also reform our global ocean governance architecture and shift from harmful exploitation to sustainable use of the ocean."
Papua New Guinea's Prime Minister James Marape said his national government does not support deep sea mining due to potentially devastating environmental consequences.
However, his stance on the issue is opposite to the one the governor of his country's New Island Province has taken.
Governor Walter Schnaubelt recently issued a statement backing Niu Solwara, the company planning to launch the controversial Solwara 1 seabed mining project in the Bismarck Sea by late 2027.
Governor Schnaubelt said the new mining techniques employed by Niu Solwara are environmentally safe.
Meanwhile, Palau's president Surangel Whipps Jr said financing is key to ensure a sustainable ocean economy that works for the planet.
He said the mechanism must include grants for science and governance, patient capital for community-led enterprises, sustainable revenue mechanisms for marine protected areas, and robust local financial systems supporting nature-positive businesses.
French Polynesia's president, Moetai Brotherson, spoke of his administration's plan to establish a network of highly protected marine areas (MPAs).
This was met with applause.
"Why do we do it? We do it because we are not just looking at the ocean; we are not just seeing it at some place that we can fish. We are part of the ocean, and the ocean is part of us."