This is the 6652nd most frequent Turkish word.
açıldığı
"Opened" or "has been opened."
In this sentence, 'açıldığı' is used in a causal subordinate clause signifying 'when it opened' or 'because it was opened'.
Kapı nihayet açıldığı için içeri girebildik.
We were able to enter because the door was finally opened.
Here, 'açıldığı' indicates a temporal context, connecting the opening of the sea season to the planning of vacations.
Deniz sezonu açıldığı zaman tatil planlarımızı yapıyoruz.
We make our vacation plans when the sea season opens.
In this sentence, 'açıldığı' is used to describe the moment of the curtain opening, which introduces the following event.