Five Britons died in October 2015 when a whale watching boat they were aboard sank off the coast of British Columbia . The vessel, the Leviathan II, was owned by Jamie’s Whaling Station on Vancouver Island, which had had a fatal accident years earlier, in 1998. Why the boat sank is unknown, although one passenger reported that a sudden wave capsized it, according to news reports. The passengers were not wearing life jackets because the boat had an enclosed cabin, and it would have been difficult to exit if the lifejackets inflated on impact, the company’s owner told reporters.

Thousands of eco-tourist adventurers set sail each year on whale watching trips, almost all of them without incident, according to the Pacific Whale Watch Association. But you can take certain precautions before leaving the dock — or even booking a trip — to ensure that you have a safe adventure.

Here are some tips from experts at Boston Harbor Cruises for the best experience in leviathan watching.

Look for an experienced crew. Going out with a crew trained in whale watching is essential, says Jeanne Sullivan, customer experience navigator with Boston Harbor Cruises, which takes passengers to view whales at a nearby marine sanctuary. Call the company and ask if whale watching is the main focus of its vessels or a sideline. Ask how much experience the crew has with whales, including what kind of training it has had and how many years of seagoing experience its members have.

Related: Cruise Vacation? Have a Safe Trip

Do your homework. Check online reviews of the company . TripAdvisor is one place to start. See if the company you’re considering holds a certificate of excellence from TripAdvisor — a mark of consistently high reviews.

Book a trip only on a vessel equipped to handle maritime emergencies , advises Sullivan. “We’re part of a research project with the New England Aquarium, and all of our boats are equipped with emergency equipment,” she says. Experienced whale watchers often prefer large, elevated catamarans that afford a better view of the creatures, Sullivan adds. Whatever boat you take, ask whether the boat is equipped with sufficient safety and life-saving equipment, including life preservers and hypothermia protection, to cover all the passengers .

Check on amenities. Are there seats on the boat and shaded areas if it gets too hot or sunny on deck? Is there a bathroom on board?

Look for an environmentally friendly company . Brett Soberg of Eagle Wing Tours in Victoria, British Columbia, recommends asking these questions (and the answers should all be “yes”): Does your hull design leave a small wake? Does it have an above-water exhaust system? Does it use a 4-stroke engine that consumes less oil and gas, and is its surface propulsion system “as quiet as rainwater”?

Related: Ocean Smarts: How to Protect Yourself at the Beach

Make sure the excursion company belongs to the Pacific Whale Watch Association and follows its “Be Whale Wise” guidelines , which are designed to protect whales. These guidelines seek to keep boats from disrupting the environment of whales and other marine mammals. In U.S. waters, there are federal laws protecting whales. Captains are required to put the boat engine in neutral not less than 100 yards from a sighted whale.

Pack for comfort . Bringing layered clothing, gloves and a warm hat may be advisable, depending on your location and time of year. “Warm clothes, for sure,” Sullivan says. “Even in the summer, when you get out on the ocean it’s a lot cooler. If it’s a rougher day on the sea, we would also recommend bringing Dramamine,” a medication for seasickness. Since you need to take it well before your excursion, you may want to call ahead to ask if the seas are rough that day.

Don’t count on seeing whales on every excursion . Captains will do their best to locate the massive mammals of the sea, but there is no assurance of seeing one. Rather than a refund, you are more likely to be given a voucher for another trip. It’s also a good idea to know how long the boat ride will last, and how much time you’ll actually spend watching whales, Sullivan says: “A faster boat will get you to the whales much sooner so you spend more time enjoying them.”

Consider buying travel insurance before your trip . It’s often inexpensive and can offers peace of mind.

Related: Who Needs Travel Insurance? You Might

Steve Evans, MA, is an award-winning journalist with more than 20 years experience in daily news, investigative, health and business journalism. Among other jobs, he has served as managing editor of the Central Virginia Newspaper Group, as a senior writer for SNL Financial and as a staff writer for The Progress Index and the Richmond Times-Dispatch.