As we wade into the blackened water with the cool night air on our faces, the moon lighting the ripples on the water's surface and our senses heightened, our instincts are making us question if this is the smartest thing to be doing.

Not far away, we hear the puff of a dolphin's breath, reminding us that we are just humble visitors in their world.

Even after over 100 logged night dive hours, I still feel that bit of excitement every time I explore our ocean after the sun has gone down.

You just never know what visual spectacles you are going to be treated to.

As it is only safe to dive the sites near Nelson Bay at slack high tide (due to strong currents at other times), we are at the mercy of nature's timing - sometimes we're in the water at quite ludicrous hours.

One evening I was approached by police officers when exiting the water at 1am, curious what I was up to.

Once you are beneath the surface, any remnant nerves are calmed, as you focus on the world illuminated by beam of your torchlight.

Everything looks completely different.

The fish you are used to seeing by day are often tucked in for the night, or they have their pyjama on (many have different colours or patterns at night).

The predatory eels, rays, octopus and bottom-dwelling sharks are more active, and there is a plethora of life buzzing around your torchlight.

Some mouth-brooding fish, such as the eastern gobbleguts (Vincentia novaehollandiae) come out from their daytime hiding spots with gobs full of eggs, much to the delight of photographers.

Curious squid and cuttlefish come in close, hoping to take advantage of small crustaceans that are attracted to the torchlight.

A bizarre-looking creature, known as the striped pyjama squid (Sepioloidea lineolate), emerges from its sandy bed, sporting its black and white stripes, and yellow beady eyes, looking like an underwater version of Beetlejuice.

Almost every patch of ocean floor has activity at night at the dive sites of Port Stephens - its world-renowned diversity of sea slugs is on full display, and sometimes rare creatures that can't be readily identified by scientists are found - such as an orange mantis shrimp that posed for me at Fly Point.

In addition to the visual overload, everything sounds different at night too - with less boating traffic, the sounds of the ocean are amplified.

Mulloway make eerie croaking and grunting sounds, and sometimes you can hear the squeaks and chattering of dolphins.

Every time we dive at night, we end up staying down far longer than planned - we always emerge buzzing with energy, wishing we could have more time than our tanks and the tides allow.

It is truly a wonderland down there.

When you are next dining at the Little Beach Boathouse and you see torchlights swimming out, don't just write us off as crazy people.

We are really just like big kids on an exploratory adventure, excited to find out which visual spectacles the ocean will be treating us to.

Meryl Larkin is a Port Stephens marine scientist and PhD researcher at Southern Cross University.