After Finnish banking credentials you can buy 14-day or 30-day HSL season tickets at student prices through the HSL app.
Complete DVV registration and open a Finnish bank account (needed for bank-ID login).
In the HSL app, go to your profile and log in with your Finnish bank ID to prove student status.
Buy season tickets (14 or 30+ days) — now at student price. Before this, you can get a temporary HSL card at the university Check-In Event for temporary student pricing.
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