Battery operated device was invented to control the speed in rhythm of the human heart which professional was mainly involved in this invention

Rune Elmqvist is designated with the credits of establishing the first artificial cardiac pacemaker.

Explanation:

I believe that ocean exploration is limited by all of the above. Lack of technology definitely affects why there is no enough exploration of oceans, not to mention the expense, how much that would cost. We also have to take into consideration weather conditions, there has to be a perfect timing.