Arrays with huuuuge number of elements

I need to save my 3-dimensional array of a custom class (it’s for a Minecraft/voxel-type of game).

I know I can’t serialize multi-dimensional arrays so I just convert it to a one-dimensional array and serialize that. No problem in theory. However, the number of elements in the 1-dim arrays will of course get very big (5 or 6 digits minimum, even smaller map sizes have 30k+). Once the elements from the multi-dim array get applied to the 1-dim array, Unity hangs up if the element number is high enough.

So, how can I serialize a multi-dimensional array of, say, 32x32x32 elements or rather, convert it into something that can be serialized so that even huge array sizes are no problem?

Thanks, of course I youse a binary formatter for the saving itself.

To answer the original question, I found out that I could just use a List and the elements to it instead of an array, and now it works.