Whats the difference between SSI and other certification agencies?
There are few standards that are different but you really get the same with each certification. Advanced Course is a good example of a difference where SSI may be a preference. SSI requires you to have 24 logged dives and certified in 4 specialties to officially be an advanced diver. With some agencies a student can finish their Open Water Certification, begin and complete their Advanced with only 10 logged dives under their belt.