Thunderbirds (1965)

S1E19 Danger at Ocean Deep

Following the mysterious explosion of the Ocean Pioneer tanker, Brains takes on the challenge of uncovering the truth behind the disaster. With assistance from Lady Penelope, he uncovers that the blast was triggered by a chemical reaction between the cargo of liquid Alsterene and the naturally occurring OD60 in the waters. Meanwhile, International Rescue mobilizes to rescue the crew trapped aboard the doomed Ocean Pioneer II.