I don't believe that one was particularly safe in its design either? Just quoting the most colorful parts of Wikipedia's history:
- "Oxygen was supplied from high-pressure cylinders carried inside the sphere, while pans of soda lime [hn: sodium hydroxide?] and calcium chloride were mounted inside the sphere's walls to absorb exhaled CO2 and moisture.[6] Air was to be circulated past these trays by the Bathysphere's occupants using palm-leaf fans.[2]"
- "Suddenly, without the slightest warning, the bolt was torn from our hands, and the mass of heavy metal shot across the deck like the shell from a gun. The trajectory was almost straight, and the brass bolt hurtled into the steel winch thirty feet [9.1 m] away across the deck and sheared a half-inch [13 mm] notch gouged out by the harder metal. This was followed by a solid cylinder of water, which slackened after a while into a cataract, pouring out the hole in the door, some air mingled with the water, looking like hot steam, instead of compressed air shooting through ice-cold water.[6]"
- "The ocean during this dive was rougher than it had been during any of their previous dives, and as the Freedom rocked on the surface, its motion was transmitted down the steel cable, causing the Bathysphere to swing from side to side like a pendulum. As the Bathysphere descended, Barton succumbed to seasickness and vomited inside it. However, the first half of the radio transmission had already been broadcast, and neither Beebe nor Barton wished to cancel its second half, so they continued their descent.[5] ... the Bathysphere was still rocking wildly and Beebe and Barton were both bruised and bleeding from being knocked about inside it."
- "During their first test dive, they demanded to be pulled up after descending only four feet (1.2 m) because the sphere had begun to leak; they soon discovered this was because Tee-Van had neglected to fasten all of the bolts that hold the hatch shut.[2] Another problem occurred on their second test dive, during which they discovered that the lower end of the rubber hose holding the power cable and phone line had begun to deteriorate, and they spent the rest of the day reversing the hose's direction so that the end which was deteriorating would be the end above the water.[5]"
https://en.wikipedia.org/wiki/Bathysphere