Deep breathhold or scuba dives by individuals for the sake of records produce little if any scientific information that benefits diving. Offshore, inland and coastal commercial divers now work in conventional surface air supplied helmet gear to depths of 180 to 200 feet.
http://www.skin-diver.com/departments/crosstalk/commdiving.asp
An atmospheric diving suit allows very deep dives of up to 700 metres (2,300 ft). These suits are capable of withstanding the pressure at great depth permitting the diver to remain at normal atmospheric pressure.
https://en.wikipedia.org/wiki/Deep_diving
The diver(s) exit the bell only long enough to perform what is (usually) a short work time. This type of diving is sometimes referred to as bell-bounce diving. Full saturation diving has been conducted to depths of nearly 2,000 feet. One classic saturation dive for a crew of eight divers was to 600 feet for 30 days.
http://www.skin-diver.com/departments/crosstalk/commdiving.asp
For the recreational diver on air, that limit is 130 feet. For the helmet air supplied commercial diver, it is probably 200 feet. For the mixed gas helmet diver, it is probably 300 feet with a bell-bounce diver going to 600 feet for short durations. For the mixed gas saturation diver, perhaps 2,000 feet.
http://www.skin-diver.com/departments/crosstalk/commdiving.asp
Depth - Recreational divers should not dive below 130 feet (39.6 m) without advanced training and equipment. The deeper you dive, the higher the risks for injury. As you go deeper, less light can penetrate the water and the ocean becomes darker.
http://www.wikihow.com/Prepare-for-Your-First-SCUBA-Dive
In technical diving, a depth below about 60 metres (200 ft) where hypoxic breathing gas becomes necessary to avoid oxygen toxicity may be considered a deep dive. In professional diving, a depth that requires special equipment, procedures, or advanced training may be considered a deep dive.
https://en.wikipedia.org/wiki/Deep_diving
How to Prepare for Your First SCUBA Dive. Community Q&A. You've got your Scuba certification, you've got your Scuba gear, and now you're itching to go on your first Scuba dive. And sure, the certification process reviewed all the basics, but there are still other practicalities that an informed diver should know.
http://www.wikihow.com/Prepare-for-Your-First-SCUBA-Dive
Scuba diving is permitted by OSHA regulations to those depths under limited conditions. From 200 to 300 feet, diving rigs using helium and oxygen as a breathing medium are used. To 300 feet, diving is usually performed on a similar mixed gas system, except descents and ascents are done in a bell.
http://www.skin-diver.com/departments/crosstalk/commdiving.asp
Even in recreational diving the meaning may vary: In recreational diving, a depth below about 30 metres (98 ft), where nitrogen narcosis becomes a significant hazard for some divers, may be considered a deep dive.
https://en.wikipedia.org/wiki/Deep_diving
How to Prepare for Your First SCUBA Dive. You've got your Scuba certification, you've got your Scuba gear, and now you're itching to go on your first Scuba dive. And sure, the certification process reviewed all the basics, but there are still other practicalities that an informed diver should know.
http://www.wikihow.com/Prepare-for-Your-First-SCUBA-Dive
how deep do scuba divers go
Scuba divers can go 300 feet deep.  Scuba divers go deep about 300 feet.