In the days and weeks and months that followed, I came across lots of people who had the same kind of visceral reaction.
It felt like someone or something you deeply love and have loved all your life had been mortally wounded, and there was nothing you could do about it.
It was helplessness, sadness, despair, rage all rolled into one.
Joining the volunteer army, sweating side by side in those sperm suits and gumboots, helped a little.
But then you'd come across some oil-soaked bird corpse, or watch the gulls trying to scavenge with their gummed-up beaks.
Now I'm back running on the beach. But it's not the same.
Often, after a stiff blow from the east, the oil comes back. Not a lot of it. Not those big stinking patties we were picking up a year ago, but it's there.
How long will it keep coming? Where is it coming from? What is it doing to the sea life, the birds, the shellfish?
Maritime New Zealand say it's not coming from the Rena, although there are still pockets of oil inside the wreck.
It could be oil that sank to the sea floor being stirred up, or oil trapped behind rocks or offshore islands getting dislodged - it's hard to get a firm answer, and there's "no definite prediction" from the regional council as to how long this will go on.
As for the ecological impact, that will take longer to measure, with one university team expecting to release an interim report next week.
They're just a third of the way through a long-term monitoring programme.
A couple of months before the Rena disaster, my husband and I took a friend from the United States around East Cape, and besides the raw beauty and mid-winter emptiness, we were struck by the abundance of "No Oil Drilling" signs along the way.
Local Maori, in particular Te Whanau a Apanui, have taken the lead in opposing plans by the Brazilian company Petrobras to explore for oil in the Raukumara Basin off East Cape, and that opposition couldn't have been clearer to us as we wound our away around the coast.
Hand-painted signs in English and Maori were everywhere, attached to trees, houses, fences, even the few stores that were open during our journey.
The signs prompted conversation to turn to the 2010 Deepwater Horizon disaster in the Gulf of Mexico, and how New Zealand would cope with an oil spill. We were soon to find out, and it wasn't reassuring.
Facing questions a few days after the Rena grounding about deep-sea drilling, John Key assured us environmental protections would be put in place.
"The prime minister would point out that there is no connection between deep-sea drilling and a maritime accident of this nature," Mr Key's spokeswoman said.
"They are completely unrelated except that they both occur at sea."
When you're standing at the water's edge watching the outgoing tide leave that gooey black signature, it's clear there's something else they have in common, and that's oil.
Still, the PM was right, there are definitely some differences. The Rena spilled around 350 tonnes of oil; the Deepwater Horizon, 660,000.
