There has been some decent advice posted. The wetsuit and shoes are a must. 28 feet may be deep enough. That is some really serious height though. The possibility of serious injury and death are present. Make absolutely sure you have someone nearby and ready to pull you out should you get knocked unconscious. Is the water murky? Fast moving? If so, definitely do not do it.
The risks are not worth it in my opinion. The extreme cliff jumps we see videos of are usually into agitated water, such as at the bottom of a waterfall. This means that there is a lot of oxygen in the water, and the surface is not a solid. You will not have this luxury. I have personally jumped 60 measured feet repeatedly, and it hurts quite a bit. There is a definite "slap" upon hitting the water. While I would jump higher, 106 feet is far outside my comfort zone.