As a Nordic citizen, you do not need to bring a passport when traveling within the Nordic region (Sweden, Finland, Denmark, Norway excluding Svalbard and Iceland). However, you should always be able to prove your identity on request. Your identity is confirmed with a Passport or National ID card.
*From 25 May 2020 before Air Leap ID and authorization check on all passengers. It is the responsibility of each passenger to be able to present correct documents for their trip / ticket.