For the pre-20th century Greek sponge-divers, equalizing of the ears was not necessary. These freedivers had burst their eardrums since early childhood, on purpose, through diving without equalization. The perforated eardrum would not heal, since they would continue diving every day. This was thought to be a small price to pay for the ability to earn a decent living via the sponge trade. This involved risks from infections and also balance problems, but it didn't seem to affect them significantly.
In general it is not clear if these early sponge divers of the Aegean knew about equalization techniques. Diving techniques were considered a trade secret and were carried from one generation to the next without much information leaking out to the competition. Even if they knew how to equalize, they would still prefer the above technique, since the amount of air lost to ear equalization is not trivial, and compromises their working depths. This fact alone explains the depths reached by Stathis Hatzis in Karpathos island, which were admittedly no less than 80 meters and probably closer to 90 m. since the bottom was at an angle, and he did several dives to locate the anchor.
-Stathis Kostopoulos