I think you will find that by 'Marine' the OP means a marine aquarium
For this application I think you will be much better off using a Constant Current LED driver, such as the Meanwell LDD series, together with a higher voltage power supply i.e. 36v or 48v.
Then you will just need to run 4 or 5 strings of leds in series rather than confusing the issue by using parallel strings and the inherent problems they have i.e. load sharing issues and the need to install fuses to protect the leds.