Methods, apparatuses and storage medium associated with navigation service are disclosed. In various embodiments, a method may include collecting, by a client mobile device, ambient barometric pressure information at a current location of the client mobile device. The method may further include providing, by the mobile device, contemporaneous navigation assistance to a user of the mobile device or for a user of the mobile device, assisted by a remote navigation assistance service. Assistance by the remote navigation service is associated with determining the current elevation level, based at least in part on ambient barometric pressure information collected by the client mobile device and by one or more crowdsourced mobile devices at the current location. Other embodiments may be disclosed or claimed.