“Press the control that says ‘Water’,” commands my co-driver Christoffer, an expert amphibious WaterCar Panther driver and my instructor. “Wait a second for it to beep. Then you’re ready to drive in the sea.”

On the dash, right by a sign that says ‘Land’ (which reverses the process), is the Water button. I press it. Fore and aft (sorry, we’re not in the water yet; front and back in car parlance) something mechanical and whirring is happening, but not that I can see. And certainly not like Roger Moore’s 007 Lotus Esprit converting to submarine mode. In reality, the Panther’s wheels are retracting partially up in to the wheel wells, exposing the flat hull to the ocean.

Avoiding the barnacled yacht tied up on the same slipway we are using to access Dublin harbour, watching out for a swan nuzzling seaweed at the water’s edge and aware of a 40,000-ton cruise liner almost filling my further field of vision I engage first gear and drive, as you do, into the ocean towards the ship.

Ireland is from where that most infamous of all liners, the Titanic, last left land. Unsinkable, they said. That’s pretty well what Dave March, creator of the WaterCar also told me. Full of foam he said, shouldn’t sink. In a first for a car test drive, I am wearing a life jacket, just in case.

Like some of the discarded whiskey bottles around us in the Irish Sea, we are soon bobbing up and down. Christoffer tells me to take it out of first gear and push down a separate alloy lever on the floor. It is for the water jet unit on the back. In seconds, the free-revving Honda 3.7-litre motor mounted deep in the hull is no longer powering the knobbly rear wheels it uses on land but now the jet. The accelerator for land is the same for sea.

“The most important thing,” he says in a sing-song Scandinavia accent but with an undertone of Viking threat, “is to remember you need power to steer on water.” He is not wrong. With no power we are a sitting duck. I learn fast that steering comes as much from the accelerator as the wheel.

Around a hundred of these US$150,000 amphibians have been hand-made at March’s Los Angeles workshop. Most live in places where the rich have their holiday homes, such as the Florida Keys and wilderness lakes in Montana, Canada or Scandinavia. The reason many buy them, says March, is to be able to pop the across the water from a private islands to the shops or for a meal and, unlike a boat, be able to drive into town when you get there.

On the street, the Panther is unremarkable as a vehicle. It is heavy to steer and, in many countries, not street legal (although loopholes seems to have been found by some owners – one even registering it as a tractor). WaterCar doesn’t advocate using it for much more than local drives and really not for freeway use. And like the old Jeep on which it is styled, airbags are not fitted.

Europe is not a major market so far for WaterCar, so this is a rare beast in these parts. This is one of the first WaterCars made and part of a stable of exotics owned by a member of the Lego toy family in Denmark – he has two. This one is their runabout. And it is in Ireland to star in a film for Circle K filling stations by towing a champion British wakeboarder up the River Liffey. Christoffer will be his driver. I get an exclusive chance to test it, sadly not from a private island but in Dublin Bay and on the River Liffey (from which Guinness thankfully does not get its water).

Given Dublin’s traffic – for a modestly sized capital – is like molasses, the appeal of bypassing traffic jams using the water is an appealing bi-product of using the city’s tidal artery. And, if I had a spare $150k to drop on a WaterCar, avoiding traffic is the reason I would buy one.

Unlike other amphibious cars like the iconic Amphicar or Dutton, the WaterCar does not chug along with its wheels still dangling from each corner. By raising them, its drag is reduced and, with 250 horsepower at hand, it can plane on the top of waves and reach a top water speed of around 80 km/h. In Dublin we are limited to just below 50 km/h. But, when you multiply the sensation of speed on water by three for the land equivalent, that’s like doing 160 km/h over a lumpy field.

Getting onto the plane takes some grunt to break the suction of the hull on the water. The gutsy Honda engine revs to over 6,500 rpm and, with only two of us in the car, bursting onto the wave tops is like riding a surfboard for the first time.

As on land, on the sea the WaterCar takes some muscle to change direction. Unlike a boat with a V-hull, it skims like a stone or slides like a rally car when turning. Add in the bumps and jumps as it bounces across the waves, keeping your foot on the accelerator is not easy. If it comes off, the deceleration is acute and coming off the plane almost immediate.

We buzz past the towering white wall of the cruise liner moored and get waves and yelps from those on their balconies. Maybe a few of these on each ship would up the fun quotient to a cruise.

The WaterCar Panther is not the best boat and not the best car but, if commuting either from your private island or through your home city is proving a chore, then it might make sense. For me and Christoffer, our next challenge is to cross the English Channel in it. Fast.