Musk retaliated by tweeting a lengthy response, including one comment that called Unsworth a paedophile.
"We will make one of the mini-sub/pod going all the way to Cave 5 no problemo. Sorry pedo guy, you really did ask for it."
He has now apologised on Twitter for the comments. Musk tweeted a story about the controversy, commenting: "As this well-written article suggests, my words were spoken in anger after Mr. Unsworth said several untruths & suggested I engage in a sexual act with the mini-sub, which had been built as an act of kindness & according to specifications from the dive team leader.
In a separate tweet he said: "Nonetheless, his actions against me do not justify my actions against him, and for that I apologise to Mr. Unsworth and to the companies I represent as leader. The fault is mine and mine alone."