I've been looking forward to a beautiful warm beach day ever since the end of summer. No, really. In San Francisco's oddball climate, some of the warmest days all year arrive in the fall (while August can be downright chilly). Just last week, the thermometer broke 70 degrees here, and we'll even have a few afternoons of glorious T-shirt weather in early December.

While the rest of the nation cuddles up to extra helpings of tasty cold-weather carbs [0], the very idea that I can hunt down new local sands to comb in November can make this former Connecticut boy almost giddy. So you can imagine how dejected I felt when 58,000 gallons [1] of "nasty," extra-thick bunker oil [2] oozed into our pristine bay from the hull of a damaged cargo ship two weeks ago. Any dreamy notions I had of late-season beach days were smashed – goodbye to all that, I thought, until next autumn (or for all I knew, much longer – after all, Exxon-Valdez [3] oil still lingers after nearly two decades).

As far as 40 miles up the coast, beaches were closed for cleanup, but could I really complain? My R&R plans were scuttled, but local fishermen were grounded (and remain so) because their haul would be toxic, while birds and sea creatures were poisoned or killed by the thousands. My mood was glum, certainly, but ecologically speaking, I was unscathed.

A friend emailed to say that the shimmering blue water usually seen from his window was now a schmear of depressing gray, which piqued by my morbid curiosity. I'd had beach on my brain for weeks – but I hadn't considered going to see this mess firsthand (from a safe distance, of course). Part of me wanted stay away, to pretend it hadn't happened. Another part didn't want to succumb to disaster. After all, I visit with friends when they're not feeling well. If I stayed indoors this weekend instead of heading out as planned, wouldn't that mean the oil spill, well, "won"?

An odd news story provided the inspirational tipping point. I read that a few innovative volunteers were capturing oil globs with mats made of human hair, and then applying mushroom spores to biodegrade [4] the gunk into safe, nontoxic compost [4]. With enough green-minded geniuses like these, I thought, our sullied waters would surely heal one day. I ventured forth towards the water's edge with a newfound, if sober, optimism.

Saturday was not as a warm day as I had hoped. I pedaled my bike under an overcast sky toward the entry gate [5] of the Presidio, a former military base turned into national parkland. As I arrived, the sun appeared fleetingly [6], like an invitation beckoning me to enter. The Presidio lies where the ocean meets the bay, and I planned to ride the snaking trails [7] straight through its heart before hanging a sharp left along the park's western edge onto our local stretch of the California Coastal Trail. Here, I would travel over coastal bluffs through mostly wild habitat, towards Baker Beach, where I could either confront a sad scene, or confirm that cleanup crews were doing a great job.

I began tracing bike route 65, past a panoramic view [8] of San Francisco Bay, Angel Island, Alcatraz, and beyond. Golden sunlight, blue sky, and a dingy cloud layer vied for my attention high above apparently gray water – but from up here, still a mile from the shoreline, I couldn't tell if the bay's drab hue was due to its oily content or the clouds above. I considered that poignant possibility, and then pedaled onward through fog-wrapped trees, before descending [9] slowly along the unpaved Coastal Trail and emerging mere feet from the sands of Baker Beach.

To my surprise, I found people hanging out and even wading as they would on any other day. Seeing them splash in the foam concerned me, but there were no closure signs to be found; perhaps it was OK. As I learned later, this particular spot had reopened the previous afternoon. However, those waders apparently didn't know (or defiantly didn't care) about public safety warnings [10] against getting wet. And how did the ocean look? Sort of normal, actually. I didn't know what might lie below the surface, but I saw no slick rainbow-colored sheen, as I expected. In the end, despite clouds and spilled oil, it was still a day near the beach.

I read on Monday that 17,000 gallons of oil had been collected so far (out of 58,000 spilled), and that hearings about the incident had begun, coincidentally, at a building in the Presidio [11]. I also learned that much of this very park I'd traversed was actually manmade, including its stunning century-old forest [12]. The human imprint upon the natural world can be ugly at times, and beautiful at others. What matters most, I believe, is how well we react when things go wrong, and that we take responsibility [13] for making things right again.