This page says it was a Y1 yield variant, 1.1 megatons: https://en.wikipedia.org/wiki/B28_nuclear_bomb https://en.wikipedia.org/wiki/B28_nuclear_bomb A Y3 wo

This page says it was a Y1 yield variant, 1.1 megatons: https://en.wikipedia.org/wiki/B28_nuclear_bomb https://en.wikipedia.org/wiki/B28_nuclear_bomb A Y3 would have been 70 kilotons, and a Y5 is the 1.45 megaton variant. > "On 6 July 1967, the Alvin was attacked by a swordfish during dive 202. The swordfish became trapped in the Alvin's skin, and the Alvin was forced to make an emergency surface. The attack took place at 2,000 feet (610 m) below the surface. The fish was recovered at the surface and cooked for dinner." I hope they stenciled a swordfish onto the sub.