it's long, but very good.
Probably not popular with many divers, but helpful for aspiring apneists who think they should be able to "train up" to do 30m deep dives and hold their breath for 5 minutes or some such.

Be reasonable, don't let record numbers fool you, and stay safe.

https://www.jp-petit.org/dangers/danger_eng/apnea_eng/apnea.htm