The present invention provides unique technology, systems and methods of cultivating different types of seaweeds, including, but not limited to, Porphyra (Nori), Laminaria, Undaria, Eucheuma, Gracillaria, Ulva, Sargassum, Codium, Cladophora, Ascophyllum, Palmaria, Furcellaria, Fucus or Enteromorpha, in land-based seawater ponds having a climatically suitable and nutrient controlled environment. These land-based ponds may be built in any part of the world with structural engineering and architectural modifications. The land based units for cultivation of seaweeds comprise phycological laboratory facilities, U-shaped sleeves, to allow the maturation of the sporelings; growth tanks, U-shaped cultivation tanks, a plurality of small inoculation tanks aerated with air, and a harvesting unit.