Question

When lava goes underwater can you touch it?

Answer 1

If lava is under water it is still hot and would burn you very bad because it might not be lava anymore but would still be very hot lava rocks

Answer 2

Sure, you can touch it, if you want fourth-degree burns all over your hands. Water will cool the surface of the lava a little bit, but it is still way over the tolerable temperature that you can safely touch.
Hope that helped =)