The Splashcloud looks mostly like a conventional ship that is hanging below a large floating balloon that provides uplift. There are several paddles attached to both the fuselage and the balloon for steering. The cabin cannot be entered.
Location in Cantermore
In Cantermore, the docking port for the airship is in the northern part of the map, up in the mountains. Ponies must travel up a long winding path to reach the airship. The portal to Cloudopolis is on the bridge from the cliff to the ship. A strong wind is pushing ponies around on these heights, so be careful not to be pushed off the cliffs.
Right next to the docking port is the Wonderbolts' HQ.
Location in Cloudopolis
The docking port in Cloudopolis is on the far northeastern corner of the city. The station actually has two portals: the one facing the Splashcloud leads to Cantermore, the one on the opposite site leads to The Heartlands.
If you go down the stairs to the station, there are paths left and right that both lead to a bottom story which offers a workbench for Artisan crafting and a portal leading to the city center on the lowest cloud level.