The longest tram line in the world is Belgium's "Kusttram". It runs the length of the Belgian coast, from Knokke near the Dutch border to De Panne, close to the border with France. It is nearly 70 kilometres in length.Trams run on-street through the centre of De Panne.
Leaving De Panne, the tram route goes onto its own alignment, segregated from general traffic.
The tram line is De Panne's principal public transport service, linking the town with other towns along the coast, including Oostende. From November until Easter, trams run every 20 minutes, otherwise they run every 15 minutes, rising to every 10 minutes during the peak holiday months of July and August.
The peak summer service requires more trams than are needed for the remaining months of the year. A number of trams are loaned from the city of Gent for July and August, to enable the 10-minute frequency to operate on the coastal service.
Other than the tram, De Panne has one bus service.Route 56 links De Panne with the nearby town of Veurne. Buses generally run hourly, with some additional journeys during the summer months. Like the Kusttram, route 56 is part of the DeLijn public transport network which covers Belgium's Flemish region.
In August 2018, I found standard single-deck buses in use. These had two sets of doors. 
A simple tariff system applies on DeLijn services. At the time or writing, a single ticket is available for €3. This applies to journeys of any length, and allows unlimited interchange for up to 60 minutes. A 10-journey ticket is available for €16. This can be used on any DeLijn service. One-day tickets allowing unlimited travel are also available, along with three-day and five-day versions.
There is also a seven-day ticket available for West Flanders province, which covers the coastal region. This costs €26 for one person or €40 for two people travelling together.
Strictly speaking, the Kusttram doesn't end in De Panne. The terminus, at De Panne railway station, is a couple of kilometres inland, in the village of Adinkerke.
At De Panne station, the Kusttram meets another bus service.
This is a cross-border service into France, operated by Dk'Bus (website only in French) as part of the public transport system serving Dunkerque.
I found an articulated bus on route 2A, linking De Panne with Dunkerque.
Since September 2018, the Dk'Bus network has operated free of charge for all passengers. This includes journeys into and out of Belgium on route 20, which has replaced route 2A.
Finally, the trains.
De Panne station is at the end of a line. Local trains run hourly to Gent, continuing to Antwerpen on Mondays to Fridays or to Brussels and beyond at weekends.
Train fares are set by the Belgian national operator NMBS/SNCB. They are not integrated with the fares of DeLijn.
