Either the lilypad islands or sanctuary zero
Below zero is WAY easier and less scary than original subnautica, and most of the good loot is in way safer places
I call squidsharks to STOP SHOCKING ME IN MY VEHICLE
For me, it's definitely the tree spires, but, with the perimeter defense upgrade, it makes every grabby boi biome safe, so, on the other hand, it might be the blood kelp zone.
Shopping?!
They can burrow through the ice, i dont think they can swim tho
Dunes is the worst fricking biome to ever exist in subnautica history, i mean, just look at the subnauticamap.io
And, as @Kaden103 mentioned earlier, DO NOT GO TO THE DUNES. IT IS A COMPLETE WASTE OF TIME AND SEAMOTHS, PLUS THERE IS NOTHING THERE TO HELP YOU WITH THE STORY AND GAME PROGRESS.
The sparse reef. it is completely safe, the only threat are bleeders, and there is some pretty good loot and stuff down there. i recommend to explore the wreck and the alien sanctuary down there. it also shares borders with the grand reef on the west, the floating island on the west but above sea level, the blood kelp trench on the east, the dunes on the northeast, and the sea treaders path on the north.