In a recent Swedish TV show, I found out about watching diving horses as some sort of entertainment, which started out in the 1880s until the 1970s with varying interest.

From the YouTube description:

A Diving Horse was actually a very popular event in the 1880s. The 'attraction' was set up by William 'Doc' Carver. The horses sometimes dove four times a day, seven days a week. There were allegations of using prods, electrical jolts, and trap doors to get unwilling horses to dive. It lost its popularity after World War II.

Here is a diving horse that jumps from a 60ft platform in 1923, USA.