There is a worldwide helium shortage. In the future helium 3 will be real valuable since it fuses easily. Scientists think they can make helium reactors light enough and safe enough to be used on space craft. The Rolex Oyster was the first really waterproof watch. Divers would use these to time their dives. But sometimes when they surfaced the crystal would pop off. It was determined the watches were full of high pressure helium. What you need is a boat a pipe long enough to reach diving depths a vacuum pump a compressor and a helium tank. Try a pipe first to see if helium will go through the walls. A watch crystal can be had for $20. Now the coast guard is not going to like that pipe if they detect it. So you need to be ready to jettison the pipe. Add check valves to keep the water out of the pipe. It may be possible to use rubber boat that will pressurize at depth to keep your pipe afloat. If the coast guard sees the boat pop up deny all knowledge. You need to get in from the start. Eventually the government will regulate and tax it then only the major players will be mining.
Depends how much is needed and how fast. An alpha emitter and beta emitter smooshing both together might create a bunch. 
Not sure if this is a serious post…
Not a diver, but is the source of helium in the watch not just from the gas mix used in the pressure chamber for acclimatisation in saturation diving…?
Correct about helium shortages being a potential problem, there’s a lot of medical applications where helium is critical, if the cost of helium were to rise significantly, these medical procedures may no longer be affordable.
Balloon releases annoy me on both the waste of helium plus the plastic waste generated, sooner they’re banned the better IMO.
If I might ask, how deeply plugged are you into the matrix? 
If it’s out its out… maybe we can make some in nuclear reactors in small quantity…
but generally unlike Oil it is a truly limited resource we are depleting
Helium 3 and deuterium fuze easier than any thing else. They are seriously thinking of mining the moon. Both are hard to store since helium is small and slick and hydrogen is even smaller without it’s electron. I don’t know how the helium is getting into the watch either the steel the sapphire or the cracks. But it does get in it is dissolved in the water. Helium comes from radioactive decay inside the earth so it will be billions of years before it runs out. I expect some one has already figured out the best materials to allow helium to pass. This will work the only question is how well it works.
“We discovered that these watches were filled with high-pressure helium.”
This is a well-known technique widely used in industry to verify the airtightness of a component (such as a watch, a laser tube, etc.).
The helium molecule is so small that it permeates most materials.
Therefore, to verify airtightness, the chamber to be tested is filled with helium; a rapid drop in pressure provides a clear indication of its seal integrity.
Helium detectors are also available: when the detector probe is brought near the test chamber, an immediate alert is triggered by a loud, aggressive alarm.
The technique applied to (CO2) laser tubes is as follows:
A high vacuum is created (using a vacuum pump followed by a week of turbomolecular pumping), the tube is filled with helium, then evacuated, refilled with helium, and evacuated again (this acts as a chamber purge).
Finally, a last fill (the third one) is performed, and the unit is checked for leaks via pressure drop monitoring and a detector.
If no loss is measurable (validation), the tube is evacuated again and filled with the specified gas mixture (any residual helium will naturally diffuse out through the material).
Note: In the case of a metal enclosure, the metal used is titanium, as it has the lowest porosity.
The seals are made of indium.
Helium is the second most abundant element in the Universe and on Earth.
It can be produced by the atomic bombardment of boron or lithium, but industrially, it is obtained by separating it from natural gas (via distillation).
It is a gas with very distinctive properties (much like water) and is an excellent heat transfer medium (for instance, if the thermal paste used in electronics could be replaced with helium, the results would be far superior).
Its high cost is primarily due to the difficulties associated with storage and transport (in addition to its scarcity in concentrated form).
OK I was wrong. I didn’t know about saturation diving even though I was aware of the history Caissons disease.