Scoop away the watermelon flesh, reserve for making smoothie or whatever you wish. We will just be needing the rinds :) Peel the green part and make sure to remove the pink part as much as you can, leaving the white part only. Rinse.
In a bowl, mix water and lime juice, then soak the white rinds for 2-2 1/2 H, drain
Place rinds into a pot, pour enough water to cover it, boil til soften
Take off from heat, let rest overnight
Drain cooked watermelon
Place the rest of the ingredients into a pot, bring to boil for 5 mins on high
Add in watermelon, bring back to boil
Simmer until thickened, 2 H
Store in jars, chilled