Usually in candle magic, you let the candle burn down until there is nothing left of the candle. At least, that’s what I was taught to do. Each to his own, I suppose.

Why the ocean specifically? Do you worship water deities (or are you asking a water deity for assistance with this spell)? If you did, that would be an appropriate place for it.

you could bury it, parafin wax will not cause any lasting harm to the enviroment, and is not toxic.

but i usually melt them down and re-use the wax. it helps to tie the energy of all of your spells together. and promote a circular energy pattern.

It depends on the deities you worship, IMHO. For instance, if you worship ocean-based deities, and were using the candle magic in conjunction with that, than the water might be an interesting place to place it — but even then perhaps consulting the deities and placing it in the ground NEAR the ocean would be better, since it would probably be less harmful to the ocean life if it were in the sand than if it were floating besides their typical food source.

I wouldn’t re-use them, as someone suggested, even for an amulet– if the energies been charged and dispersed with a specific intent, then dedicate the candle to that purpose and let it be. Re-using them can sometimes cheapen the effect, especially if there’s any residual energies within the candle, that would get tainted by re-using them.

If you live in an urban area, and have difficulty FINDING dirt or the like to bury them (or are afraid of the local scorn of doing so in a public park, etc), than you could simply dispose of them with the regular garbage, PROVIDED they had their own seperate bag (so that the sacrifice of the candle isn’t as tainted with a rotten bannana sitting on top of it).

Really, it’s your choice, but try to be as eco-friendly about where you dispose of it as you can.