Challenging human endeavors involve risk.

My son has done triathlons, and his good friend competed quite well in that particular one.

That tragedy was very sad and cast a shadow over the whole event.

That said, I bike and run and was interested in triathlons myself at one time (no longer) but I have never had a real desire to swim for distance in a large group like that.

Just me. Swimming is tremendous exercise and I enjoy it and echo what others have said here as to its benefits.