This is a common issue that comes up, so for the interest of others I thought I'd once again provide the answer.
PROBLEM: WiFi-only iPad models (ones without cellular network capability) do NOT have an in-built GPS receiver, which means that when you are without an internet connection you cannot get location
services to display position data on a map - even if using our offline capable navigation app
ExplorOz Traveller.
SOLUTION: Your only option if you have a Wifi only iPad is to use an external Bluetooth GPS receiver. These are readily available to purchase for around $60-$250 dollars either online or in stores such as JBHifi. These actually work very
well. Popular models are Bad Elf, Garmin GLO, and Dual Electronics XGPS.
MYTH: I can share the GPS in my phone to my iPad by using the Personal HotSpot feature. INCORRECT
REASON: The GPS chip in your phone is only a "receiver" and has no ability to transmit regardless of what connection
services you have available (eg. Bluetooth, USB, Wifi, 3/4G). When your iPad uses your phone's HotSpot it receives data via an internet connection. The location
services the iPad receives during that connection is broadcast from public HotSpots & Cell Towers and never uses the phone's inbuilt GPS.
WHERE DOES LOCATION DATA COME FROM?
GPS stands for Global Positioning System. GPS uses a system of many satellites that orbit Earth to send location and time data to GPS receivers that are on the ground. GPS receivers can be stand-alone devices or built-into Smartphones/tablets as a data chip.
But, there is also another system for obtaining Location data that does not use the satellite system and instead uses Wifi/mobile data and a system called AGPS. AGPS retrieves location data from local objects on the ground such as public Wifi nodes and Cellular towers. This data is available to devices that have Wifi or 3/4G.
HOW DOES A SMARTPHONE/TABLET USE LOCATION DATA?
Although many "Smartdevices" (phones/tablets) will have a GPS receiver built in it can sometimes be problematic as more than 4 satellite fixes are required and this is often slow to achieve. So, these Smartdevices also feature the ability to automatically detect others ways of getting position data, so in urban areas the AGPS is often quicker so your device will tend to favour this option if available (ie. Wifi or 3/4G required). NOTE: in your device Settings you will also have the option to select which location
services you allow your device to use. A Smartphone/Tablet with a built in GPS will also know when the network coverage is poor and will then switch automatically to using the GPS via satellites.
HOW DOES A WIFI ONLY IPAD GET LOCATION DATA?
Since the AGPS is not available to the iPad when offline, and a Hotspot from another device only supplies internet not location
services, and the Wifi only iPad does not have the inbuilt GPS chip, it fails to be able to get location data when offline. This is why you must get an external GPS receiver (usually connected via Bluetooth or USB) for your Wifi only iPad to get consistent location data when travelling.
If you want to read it put another way, this link explains it rather nicely too-
How does GPS work on my phone.