Besides adding swamping, here are some more suggestions:
Typical Druid Spells Prepared (6/7/6/5/5/4; save DC 19 + spell level);
0 – create water, detect magic, guidance, know direction, purify food and drink, read magic;
1st – charm animal, detect animals or plants, entangle, longstrider, obscuring mist, speak with animals, summon nature's ally I;
2nd – bear's endurance, bull's strength, cat's grace, chill metal, fog cloud, gust of wind;
3rd – call lightning, quench, sleet storm, water breathing, wind wall;
4th – control water, dispel magic, freedom of movement, ice storm, scrying;
5th – call lightning storm, commune with nature, control winds, summon nature's ally V.
For control aquatic creatures, here are two possibilities:
Control Aquatic Creatures (Su): Oceanus can rebuke, command, or bolster water creatures as an evil cleric rebukes undead. He may use these abilities a total number of times per day equal to 3 + his Charisma modifier.
or
Control Aquatic Creatures (Su): Oceanus can use dominate monster (aquatic creatures only) at will. Caster level 20th.