Digging down to void/How deep is seabed layer?

[Kaldari]

I created an island in what was deep water, and began digging to create a cave entrance. I've been digging for a while, but still not into the cave layer yet.

There is almost definitely void beneath me, but it used to be possible to open an entrance (if the entrance was then sealed, that tile became dirt).

So...is the seabed just really deep, and I need to keep digging, or is it not possible to reach the cave layer when above void?

[TheLukeyBoi]

It is possible in some places to dig until it forms a cave entrance. But like you're saying the game has had particular area where it seems limitless in the amount of dirt and rock it provides. In my interactions with the void we have tried teleporting into it with a magic wand to see if the game would let us go into it (no success there) we have dropped many of number of items into it and have had some dialog ques "a horrible chill runs down your spine" and if the item is of high enough value "you hear a faint ring" (the quotes might not be exact but they're along those lines). So it would stand to reason there's things in place to stop you from going into it in the ways you are trying.