Airship unlocks at stage 10000 which provides a variety of additional features.
Firstly, airship gives access to unit seals, earned when you complete airship exploration. Certain unit seal combinations form stone tablets, which give access to extra buffs that increase based on the rank of the unit seals that form the stone tablet. The stone tablet combinations have 2 effects, 1 effect which only activates when the units that match to the unit seals are in your stage climbing team, and a passive effect which is active regardless. Unit seals also give tribe friendliness which, combined with some pets, can give a massive amount of tribe friendliness.
Airship also gives access to Daily Exploration, which you can complete for bonus unit seals as well as equipment enhance materials, which are used to give units bonuses to attack/health/defense in the form of percentages. There are 4 levels of daily exploration, which gives 4 different levels of equipment enhance materials. In order to gain access to higher levels of equipment enhance materials, you need a higher daily exploration level. To gain said daily exploration levels, you need to complete daily exploration, each completion giving different amounts of xp depending on the level of the exploration. Daily exploration levels also increase the amount of equipment enhance materials you gain from daily explorations. However currently the max daily exploration level is 9. The xp gap from level 8 to 9 is very high, but the increase in rewards per complete daily exploration are also just as high.