Where did you get that image? O_o
Anyway, Sea King stomps.
Zoro takes this with mid-difficulty. Sea King only seemed to be hyped up because he defeated a bunch on C- Class Heroes and 1 A-class Hero, not including the two prisoners which would be classified as A-class. Most of the Sea King's attacks did like large building level damage, not the mention Saitama jab was like muti-cityblock one-shot the Sea King. Zoro has way more tenacity, and durability than the Sea King, not to mention his destructive capacity is way higher than and thing the Sea King can take.
@SilverSavage: He beat two S class heros (Huff Puff and Genos) and casually broke through a nuclear shelter/dome.
Also, should be noted Genos punched Sea King through the said nuke shelter. Meaning he had easy durability to tank nuke level force to his face.
Zoro is seriously in for a lot of hurt here. Those attacks of his arent cutting too deep. Think of Diamond Jyouzu. He was able to reflect (divert) an attack from the schichibukai Hawkeye Mihawk. Sea King will not have trouble here. If anything the only advantage Zoro would have is his speed. But Sea King is easily faster than the speed of sound when he is hydrated. So really, its a 50-50 IMO.