Dysentery, Scurvy from the trip and food in general. It's why the Galapagos became a pit stop for awhile and they'd roll Tortoises onto the ship as rations later, It apparently tasted good but being a time where everyone was malnourished, the bar was pretty low. Giant tortoise was a part of sea fare. and now their endangered.
I would say maybe the author makes one of the main characters lose a shoe or falls on the ground and has to go to the hospital. as these things arnt people or animals so they won't be considered antagonists.
