I would ask the question ‘What is not Shiva?’ Is Shiva somebody? Is he a form? Is he someone sitting in some place? No! Shiva is the entire universe. He is in every atom of the universe.
Shiva doesn’t have a body, he was never a person at all. To symbolize the unfathomable, the infinite divinity, and to make it comprehensible for young people, for children and others, they made a form. In fact, there is no form to Shiva.
Shiva is a principle (Tattva) from where everything has come, everything is sustained in it, and everything dissolves into it. Shiva is the space, it is the consciousness.
There is no way that you can even step out of Shiva at anytime because Shiva is the summum bonum of the whole creation. That is why Shiva’s body is depicted in blue because blue signifies the sky; the all pervading infinity which has no limits, and no shape.