TeleportBoats is a Valheim mod compatible with version 1.0 (Deep North) that brings your nearest boat through portals and dungeon transitions. Hover over a portal and press Shift + B; your boat follows after you arrive, provided there is safe water nearby.
If no safe landing is found, the boat stays behind while you teleport normally. Synchronized server rules and personal preferences control transitions. Install the mod on the server and every participating client.