These are long and mostly high-cost tours, which puts TourRadar in a different market from much larger (and better funded) online travel rivals GetYourGuide and Klook. These companies do more high-volume excursions and museum trips.

But despite being less well known, TourRadar is doing well and has been around since 2010. Investors are also interested. The companies raised $50m in mid-2018, six months on from a $10m Series B in late-2017 and $6m in 2016.

Notably, TourRadar has TCV as one of their main investors, a firm which has backed several industry-leading companies in recent years including Airbnb, Expedia, HomeAway and Zillow.

The company says that it sees the big established travel agencies as its biggest competitor and works with more than 600 large and small local tour operators across Europe, Asia, the Americas, Australia and New Zealand.

Another upcoming startup in this space is Berlin-based Tourlane, which organises exclusive multi-day trips and raised $47m last year.

A valiant contender in this mele is the Austrian startup Robo Wunderkind, which has a Lego-like building kit allowing 5-10-year-olds to make robots that can see, move and light up.

One of the best features is that Robo Wunderkind also sells Lego adapters so that kids can put together a robot that uses both Lego bricks and Robo Wunderkind modules. The iPad app, Robo Code, allows kids to put together simple algorithms.

Robo Wunderkind initially raised around $250,000 on Kickstarter back in 2015. In 2018 it raised €1m from SOSV, Austrian Federal Promotional Bank and multiple business angels.

The trouble is that toy coding is a tough market, so it remains to be seen how Robo Wunderkind will take on the competition – much of which is from very large toy producers.

But it’s a tough market out there, in part because of the popularity of the US giant Coinbase and also others moving into the space. For instance, Revolut, the London-based challenger bank, is now offering cryptocurrency trading for premium customers.