In the early part of the 20th century, American physicist and chemist, Professor Elihu Thomson—the person credited with putting the eventual use of helium on the diving menu—had originally proposed the use of hydrogen as a suitable replacement for nitrogen in the breathing mix used by divers. David Strike has the story.

As any underwater photographer can attest to, water and electronics do not mix. Despite our best attempts at planning for unforeseen circumstances, the law of averages dictates that things can and will go wrong. More often than not, some situations are ones we had not even considered. Peter Symes and Scott Bennett report.