A321 Captain reported a hydraulic system malfunction resulting in a diversion to the nearest suitable airport.

Narrative

I operated flight from ZZZ1 to ZZZ2. About one hour and fifteen minutes into the flight; an ECAM CAUTION message Y RSVR LO LVL was displayed on ECAM and we proceeded to take appropriate action as stated in our operational manual. The First Officer stated my aircraft" and continued to act as the pilot flying; I identified the problem; and executed the appropriate actions (QRC; ECAM actions and QRH follow ups). During the system review portion of the ECAM actions; we noticed that the entire Yellow hydraulic reservoir was empty and; consequently; the system was rendered inoperative.That became an area of concern to us; as the location of the hydraulic fluid became unknown and the potential for further complications was present. Additionally; secondary failures were associated with the loss of this system. ZZZ2 was three hours away; so it was quite evident to me that even though the aircraft did not suffer a controllability impairment; it was not at state that could be prolonged until reaching destination. Once the appropriate actions were completed; we computed the required landing distance for the present weight and reviewed the QRH procedures for overweight landing. I looked for potential diversion airports with runways longer than 8000 feet. There was a long area of severe weather to our left (south of our course) and the first airport that presented a long runway and was clear of weather was ZZZ. Jeep FD pro runway length filter and weather function; used in combination with the aircraft navigation display and onboard weather radar; was a great tool to enhance situational awareness and assist in the development of a plan. Subsequently; I transferred the radios to the First Officer and contacted Dispatch through Satellite phone and we established a three way communication with maintenance. I described the situation to maintenance and my decision was to divert to ZZZ. Maintenance advised the appropriate personnel at ZZZ and Dispatch provided me with weather and NOTAMs needed. A few minutes later a Yellow pump overheat was generated by ECAM and we completed the appropriate actions again.Then; I proceeded to call the Purser and informed her of the situation and the need of a Precautionary Landing. I made a public announcement and informed the passengers of a mechanical discrepancy that required us to land at ZZZ and the presence of safety vehicles upon our arrival. The First Officer did a great job flying the aircraft; and preparing for arrival at our diversion airport. I resumed the operation of the radios and [advised ATC]; stating the reason for the diversion; souls onboard; fuel in minutes and airport requested. The First Officer and I reviewed the status of the systems affected one more time and discussed the threats present on this flight. I further reviewed the Overweight Landing procedures once again and proceeded to brief the approach.I informed the First Officer that I was going to perform the overweight landing; so I assumed the role of Pilot Flying and complied with the corresponding procedures. The First Officer reminded ATC of our status and the need of a tow track due to our inability to taxi off the runway.Once we landed; I advised the passengers to remain seated and that in just a few moments we were going to be towed to the gate. ARFF (Airport Rescue and Firefighting) was standing by; maintenance and ground personnel communicated with me via inter phone and they towed us to the gate. Once we arrived at the gate; I greeted the passengers and made the corresponding entries into the maintenance logbook.Once the passengers deplaned; I requested the Flight Attendants to have a debrief in which I shared the details of what happened; the reasons for the diversion; the importance of the system affected; and the tasks the we were performing on the Flight Deck. They shared with me what happened in the Cabin and we left to the hotel.I would like to point out that everyone involved in this mechanical diversion did an outstanding job. The First Officer supported me at all times while ATC provided the right information without introducing any additional distractions or workload. The Flight Attendants were calm and prepared the Cabin for a Precautionary Landing. ARFF was standing by at the right time and the right place. Ground personnel and Maintenance were waiting for us and accessed the runway to tow us to the gate expeditiously. The gate agents were standing by; connected the jet-bridge to the aircraft and deplaned the passengers without any delay. Contract Maintenance started to work on the aircraft immediately to open the cargo doors so the passengers' luggage could be accommodated.Finally; Technical support called me to discuss some details of the failure and I was positively impressed by the thorough and conservative approach they were planning on following. In other words; the positive outcome of this situation was the result of great teamwork.Great teamwork helped mitigate the risks associated with the problem encountered above.The cause of this event was maintenance related; so they will have the appropriate information to prevent it from happening in the future."