Check this out: design for a floating laboratory/restaurant/accomodation. Could be winched underwater for added versatility. Using roman concrete in a marine environment would mean it just got stronger and stronger. Think concrete can't float? Then revisit your school science books!

4

Releasing sharks into a no-fishing area.

Video of my shark conservation programme in Chonburi province near Bangkok. Bamboo sharks can be found for sale, alive, in some of the local fish markets so I try to find gravid (pregnant) females, place them in quarantine for a few days until they start laying, then release them and their eggs onto shark-depleted reefs. This video shows two gravid females and one male being released into the no-fishing zone administered by Thai navy SEALs in Samaesan. It's pretty rare to have the opportunity of diving on an unifished reef and always exciting to see the size and variety of local fish!
https://www.youtube.com/watch?v=w5V6t1SoL5E

Envirodiving and  reef shark release vlog:

https://www.youtube.com/user/tribalisation

Also travel in some fairly core places.

Stratospheric launch pad.

Problem: the cost of sending cargo to space is prohibitive due to the exponential cost of the fuel/weight ratio: more fuel is needed to lift the fuel that fuels the different rocket stages. Rockets also burn a lot of oxgen out of the atmosphere while releasing significant amounts of carbon into it.

Solution: launch rockets from higher up in the air. Following the example of Felix Baumgartner's Redbull Stratos skydive, amd numerous eucational experiments, here is a plan for a stratospheric launch platform, as briefly considered for publication by the JBIS.