The multi-day tour market — think river cruises, group bicycling tours, and hikes up Mount Kilimanjaro — is growing but, like a lot of other areas in the sector, it remains mostly offline.

Solo female travelers appear to be turning to group travel in larger numbers, and one consumer site specializing in multi-day tours is trying to position itself to take advantage of the trend.

TourRadar, which specializes in these several-day tours, announced that it raised $10 million in a Series B funding round.

Endeit Capital led the investment, with existing investors Cherry Ventures and Hoxton Ventures also participating.

Founded in 2010, the Vienna, Austria-based company has raised $18 million to date. It plans on using its latest funding to double its headcount, from its current 85 full-timers, mainly by hiring technical and product workers. It aims to also use the funding to step up its marketing on Google, Facebook, and other channels.

Travis Pittman, co-founder and CEO, claimed that 90 percent of multi-day tours are still booked offline via travel agents, leaving a large market to scale up that has lucrative  commissions on high-priced transactions.

The customers for multi-day tours are distinctive. For example, about 70 percent of TourRadar’s bookers are women. Looked at differently, 41 percent of its customers are solo female travelers and 18 percent are solo male travelers. This demographic appears to be turning to group travel in larger numbers. TourRadar claims its revenue between January and September of this year is double that of the same period a year earlier.

Strengths and Weaknesses

TourRadar is rare among tours and activities companies for focusing on enabling bookings multi-day tours. That focus has had pros and cons.

On the plus side, the focus makes it stand out in the market from a branding perspective. The specialty has also let the company avoid the bruising market share battle among better-known sites that mostly offer day-of activities. Among them are Viator, which was acquired by TripAdvisor for $200 million a few years ago; GetYourGuide, which has raised about $95 million; Peek, which recently acquired rival Zozi; Musement, which has raised $16.5 million, and Airbnb has been tip-toeing into facilitating peer-to-peer experiences.

The flip side is that its total addressable market is much smaller than the day-of, in-destination market that others, like TripAdvisor’s Viator, are championing. That limits TourRadar’s potential growth.

In its favor, TourRadar says it has signed up 500 tour companies, including most of the best-regarded ones, such as G Adventures, Intrepid, Topdeck Travel, and Contiki, as well as local tour companies. Two of its fastest-growing partners are Arctic Adventures of Iceland and Intro Travel of southeast Asia.

River cruising remains a growing trend, and TourRadar has Trafalgar, Uniworld, and others in its fold.

Counting against it, TourRadar has raised only a total of $18 million, while GetYourGuide, for example, has raised nearly $100 million. So what contributed to many of the seasoned travel-focused venture capital firms taking a pass on TourRadar over the years? Was it a misunderstanding of the multi-day tour space? Or was it something about TourRadar, in particular?

In any case, TourRadar found a lead investor in this Series B round, an Amsterdam-based growth capital firm that doesn’t have much travel industry experience.

Also of concern is Expedia as a potential rival. The company is increasingly dabbling in multi-day tour inventory — though it has nowhere near TourRadar’s scale. Neither of the other two industry leaders, Viator nor GetYourGuide, have shown interest in the complex segment.

To build a defensive moat against competitors, TourRadar needs to build up its “instantly bookable” tours. Today, consumers can only book about 3,000 of its 20,000 tours relatively quickly and with a minimum of back-and-forth between the customer and the tour company.

TourRadar also could be more creative in up-selling customers on insurance products. That’s because typical multi-day tours are non-refundable within a month of departure yet they often take place in parts of the world prone to political, natural, and other disruptions.

Photo Credit: Multi-day group hikers trek Peru from Aguas Calientes to Machu Picchu. TourRadar