The 6th Bomb Group

Despite the caption, this aircraft appears to be floating off the east coast of Tinian, not Iwo.

With Iwo Jima fogged in, the crew of this 6th Group aircraft had little choice.
They ditched as close to the shore as they could an swam the rest of the way. [USAF]
[Source: "B-29 Superfortress in Action", Squadron Signal Publications, Aircraft No. 31, p. 31.]