CLAYTON — I’ve hiked the Pacific Ocean floor.

Or, more precisely, what was the ocean floor a mere 4 million years ago.

The geological wonders of the 20,000 plus acres that Mt. Diablo State Park encompasses are just part of its appeal.

The short list includes hiking, bicycling, horseback riding, rock climbing, wildflowers, camping, picnicking, and stunning views.

It’s also perfect for a “Sunday drive” all the way to the summit of its namesake peak.

Once there, an observation deck — depending on the clarity of the skies — can allow you to make out such Northern California landmarks as:

* Lassen Peak responsible for the last volcanic eruption in California just over a century ago.

* The 211 acres of the Farallon Islands in the Pacific Ocean some 28 miles west of San Francisco.

* Sentinel Dome guarding Yosemite Valley.

* The Golden Gate Bridge and less famous water crossings such as the Antioch Bridge.

Take along some binoculars and you can spend a good hour scanning the horizon for landmarks.

Altogether, in the past 32 years, I’ve ventured into the state park almost 30 times.

To be honest, I usually head toward the Diablo Range trifecta — Mt. Olympia at 2,946 feet, North Peak at 3,557 feet, and Mt. Diablo at 3,835 feet.

And I prefer to use the lesser traveled trails from the east.

I start the eastern ascent at the turnout by the Sharkey Road Gate at emergency call box 16 just outside of Clayton.

Rarely, do I come across more than six people between the Sharkey Road Gate and Mt. Olympia. You typically run into that many people in an eighth of a mile from any of the other entrances.

Yes, the biggest part of the trail is fairly steep and narrow but that is the small price to pay for the solitude and the endless vistas.

If I am only in the mood for a short hike, my go to peak is Mt. Olympia.

The first three miles from Marsh Creek Road to reach Mt. Olympia is anything but flat with a nice net gain of 2,000 feet.

That satisfies my desire at times as an elevation gain junkie.

Toss in all three peaks and you can pile up more than 4,000 feet of elevation gain.

Mt. Diablo State

Park has a lot to offer

If you’re into hiking, the state park has 37 established trails ranging from 3.6 miles to 27.6 miles in length with almost 200 miles overall of trails and dirt roads.

If you’re into bicycling it’s tough to beat the grind of the 10.3-mile climb from the park boundary in Danville to the Mt. Diablo summit parking lot and the exhilarating downhill that follows.

If you’re into wildflowers there are 20,000 plus acres just starting to bloom that, thanks to an extended rainy season, should offer a vibrant palate long into May this year.

If you’re into breathtaking vistas and aren’t into hiking or bicycling it’s an easy and scenic drive to the summit where an observation deck gives you one of the best viewing decks in North America.

On clear days this time of year — especially after rain — from the Mt. Diablo summit you can make out part of Mt. Shasta 240 miles to the north, the Farallon Islands 60 miles behind the Golden Gate Bridge to the west, and parts of Yosemite Valley 135 miles to the east.

If you’re into rock scrambling and basic rock climbing, the sandstone rock formations complete with miniature turrets, caves and grottos in Rock City 3.3 miles after you cross into the park via South Gate Road is tough to beat.

If you’re into camping, horseback riding, mountain biking, or just enjoying a lazy day in a natural setting, you can do that as well.

And if you’re into geology the forces of the North American and Pacific tectonic plates brushing up against each other have created an outdoor laboratory.

How Mt. Diablo was formed

A short geological lesson: Mt. Diablo at 3,835 feet wasn’t always among the tallest peaks in the San Francisco Bay Area.

Some 4 million years ago, volcanic rock beneath 161 million years of sedimentation from the North American tectonic plate forced its way between that plate and the Pacific tectonic plate.

At first, the peaks of the Diablo Range were low and gently rolling hills. But as upward pressure continued, it thrust sedimentary levels up at an angle.

You can visually see cross-sections of millions upon millions of years of the handiwork of nature’s forces throughout the park.

It may not qualify as a super bloom but portions of Mt. Diablo State Park will definitely be ablaze in color in the coming weeks and months.

The most popular destination in the state park that is open daily from 8 a.m. to dusk is the summit observation area and visitors’ center and museum. The museum itself is open from 9:30 a.m. to 4:30 p.m. and has a small gift shop.

The displays will give you a good feel for the wildflowers as well as animal and bird life.

Panels dealing with the formation of the Diablo Range and the incredible variety of sediment and rock formations you can find in the park are worth studying as you can get a true appreciation of some of the geological features you can hike to and by. The actual summit marker that also served as the basis of surveying two thirds of California and parts of Nevada is found attached to Mt. Diablo’s peak that the summit museum was built around.

If you have binoculars, be sure to take them with you to search for a variety of manmade features you can’t make out with just the naked eye. That said there is plenty to see without the aid of magnification such as the Golden Gate Bridge.

There are endless places to explore around Mt. Diablo. When the 20,000-acre state park is combined with adjoining regional parks and preserves there are more than 90,000 contiguous acres.

Roaming those 90,000 acres is an abundance of wildlife. The most common non-pedestrian wildlife I’ve come across in my various excursions to Mt. Diablo State Park is wild turkeys. The rarest find was a bobcat that ran across my path and that of another hiker I was with last February.

Some words of caution. Take plenty of water when you hike plus let someone know where you are going and when you will return. Keep in mind cell service doesn’t exist in many areas of the park. Trail maps are a plus.

There is plenty of poison oak so keep on the lookout when you’re walking narrow trails or cutting cross country. Ticks can be an issue from fall to spring in grassy areas. Be sure to check yourself and children frequently.

I’ve only come across one rattlesnake at Mt. Diablo State Park and it was sunning on a rock 12 feet below the trail I was on. I’ve had close encounters with rattlers elsewhere. Just keep in mind they won’t attack unless they are cornered or disturbed. That said, it is real easy to keep your distance.

Mountain lions are rarely sighted on Mt. Diablo. The only place I’ve ever “encountered” one was in Death Valley walking along the lip of a canyon some 100 feet above me.

Great place for wildflowers

The absolute best excuse to pencil in a trip to Mt. Diablo in the coming weeks are for wildflowers.

A few of the native wildflowers below Mt. Diablo include:

* California Golden Poppy: It is almost a year-round flower on Mt. Diablo with most blooms between March and October below 3,500 feet in grassy areas. The biggest treat are mass blooms typically blanketing hillsides along the North Gate Road between mid-April and the early part of May.

* Manzanita: The common shrub offers delicate pink or white blooms from December to March in delicate bell-like shapes. The rain and cooler weather may prolong the blooms.

* Chaparral Currant: This shrub also features pink flowers and has been in bloom since December at the lower elevations. Expect to see them in bloom through about May near Mt. Diablo’s summit.

* Milk Maids. The white flowery plants are part of the mustard family and will be in abundance until they start fading away in May.

* Indian Warrior: The striking reddish leaves start popping up among the pines at the lower elevation in March and then finish up blooming in April near the summit.

* Shooting Star’s Mosquito Bills: The pink flowers appear in mass from mid-February through April.

* Mountain Violet: The purplish flowers are common from March to May.

* Johnny-Jump-Up: Also found from March to May, they can’t be missed thanks to deep yellow blooms with streaks of black.

* Jim Brush: The member of the California lilac family offers blue blossoms from late March to early May.

* Buck Brush: A personal favorite of mine due to its scent that smells like freshly popped popcorn, it is now in bloom through late May.

Those are just a few of the wildflowers you can find on Mt. Diablo.

In reality, you don’t need to soak up wildflowers to have a visual feast visiting Mt. Diablo. This time of year, the hills are a lush green compared to the golden hues of late spring, summer, and fall.