Vacuum Airship

With the advances in tech, a vacuum airship might be possible in the Blue Planet future.
And with an electric drive powered by solar and/or fuel cells would be a useful vehicle on Poseidon:

• It can stay in the air basically indefinitely, making it useful for long-haul transport or exploration. Or as a flying base camp or hospital.
• It does not need any infrastructure to start or land.
• It could transport huge amounts of cargo at a time.
• And with futuristic manufacturing, these could basically be like ocean cruisers but in the skies.
• They would be more expansive than ships, but probably faster. And - depending on the flying fauna of Poseidon - safer than dealing with the ocian critters.