Investors want clear ocean management rules (and likely subsidies) to scale up funding

While a step up, the total figure falls far short of what is needed. Between 2015 and 2019, only $10 billion was invested against the UN estimate of $175 billion in required annual funding.

"Public finance isn't enough but private finance is even less. So I think it's a space in its infancy," said Francine Pickup, Deputy Director, Bureau for Policy and Programme Support at the UN Development Programme.

Pickup said improving the policy backdrop and regulation, including removing subsidies she said encouraged harmful practices such as overfishing, was key, followed by the creation of a pipeline of investments including in start-ups focused on ocean-related technology.