Block Island doesn’t get talked about as a snorkeling destination the way warmer-water islands do, and that’s a mistake. The waters around this Rhode Island island are cleaner and clearer than most of the Northeast coast, the rocky shoreline creates excellent habitat for marine life, and on a calm summer day you can see 15–20 feet down through the Atlantic. What you’ll find down there — lobster, black sea bass, tautog, spider crabs, sand dollars, hermit crabs, sea stars — is worth the effort.
This guide covers the best snorkeling spots on Block Island, what conditions to look for, how to gear up, and what to realistically expect.
Is Block Island Good for Snorkeling?
Yes, with appropriate expectations. This is the North Atlantic, not the Caribbean — water temperatures peak around 68–72°F in July and August, and visibility varies significantly with conditions. On a calm day after a stretch of settled weather, visibility can be impressive. After a storm or on a windy, choppy day, forget it.
The best snorkeling on Block Island is rocky-bottom snorkeling: exploring structure, watching fish hold in current, finding lobster under ledges. If you’re expecting coral reef snorkeling, this isn’t it. If you’re excited about seeing the actual ecosystem of the cold Northeast Atlantic up close, Block Island delivers.
Best Snorkeling Spots on Block Island
Crescent Beach (Fred Benson Town Beach) — Best for Beginners
The protected, north-facing stretch of Crescent Beach is the easiest entry point for snorkeling on Block Island. The sandy bottom in the shallows transitions to scattered rock as you move out, and the calm conditions (protected from prevailing southwest winds) make it forgiving for less confident swimmers.
What to expect: sand dollars, hermit crabs, small flounder, the occasional striped bass. Not the most dramatic snorkeling on the island, but the safest and most accessible.
Access: 5-minute walk from Old Harbor. No fee.
Southwest Point — For Experienced Snorkelers
The rocky structure at the island’s southwest corner — the same area that makes it great for surf casting — creates the most interesting snorkeling habitat on Block Island. Kelp-covered boulders, surge channels, and rocky ledges hold tautog (blackfish), black sea bass, lobster, and a full suite of smaller reef species.
This is not beginner snorkeling. The surge can be significant, there are no lifeguards, and conditions change quickly. Snorkel here on calm days only, with a buddy, and stay within your ability. The reward is the best marine life on the island.
Access: Follow Mohegan Trail west past the Southeast Lighthouse to the Southwest Point area. Rocky entry.
Grove Point / North Shore
The north shore has rocky structure with calmer water than the south shore on most summer days. Grove Point and the surrounding areas offer good snorkeling in 5–15 feet of water over rock and gravel bottom. Good for crabs, urchins, cunner, and small bass.
Access: Accessible via the Greenway trail system or by bike along Corn Neck Road.
Great Salt Pond (New Harbor) — Unique Calm-Water Option
The Great Salt Pond — Block Island’s protected inner harbor — offers completely different snorkeling: calm, warm, clear water (it heats up faster than the open ocean) with a sandy-to-muddy bottom. You won’t see reef fish, but you will see fluke sitting on the bottom, spider crabs, and plenty of baitfish. It’s also a good option on days when ocean conditions aren’t cooperative.
The area near the inlet where the pond meets the ocean has the most interesting structure and current.
What You’ll See Snorkeling at Block Island
Fish species: Tautog (blackfish), black sea bass, striped bass, cunner, scup (porgy), winter flounder, summer flounder (fluke), bluefish, Atlantic mackerel (in season)
Invertebrates: American lobster (under ledges), spider crabs, green crabs, hermit crabs, sea stars, sand dollars, moon snails, periwinkles, sea urchins, mussels
Other: Harbor seals are present around Block Island from late fall through spring (they follow the fish). In summer, you may encounter menhaden schools, Atlantic silversides, and sand eels in the shallows.
Best Time to Snorkel Block Island
July and August are the best months. Water temperature is warmest (68–72°F), days are longest, and settled weather creates the calm conditions you need for good visibility. Even in peak season, choose morning sessions — afternoon southwest winds build chop on the south and west shores.
Late June and early September can be excellent. Fewer people, similar water temperatures, and some of the clearest visibility of the year.
Water temperature guide:
| Month | Approx. Water Temp |
|---|---|
| June | 58–65°F |
| July | 65–70°F |
| August | 68–72°F |
| September | 65–68°F |
| October | 58–62°F |
A 3mm wetsuit is recommended for most snorkelers in June and September. July and August are manageable without one, though longer sessions will get cold.
Gear: What to Bring and Where to Get It
Block Island does not have a dedicated dive or snorkel shop, so bring your own gear from the mainland or pick up basics on the island at one of the general outdoor retailers. Full rental gear is not reliably available.
Essential gear:
- Mask and snorkel (bring from home — rental quality is unreliable)
- Fins (full-foot fins are fine for calm-water snorkeling; open-heel fins are better for rocky entries)
- Wetsuit (3mm is sufficient for summer; 5mm for June/September)
- Water shoes or dive booties for rocky entries
- Defogger solution for your mask
Optional but useful:
- Underwater camera or GoPro (the marine life is worth it)
- Surface signaling buoy if snorkeling offshore
- Dive flag if venturing beyond the swimming area
Check in at water sports rental shops at New Harbor when you arrive — some carry limited snorkel gear and can tell you current conditions.
Safety: What to Know Before You Get In
Block Island’s waters are cold, the currents around the island can be strong, and some snorkeling areas have no lifeguard coverage. A few rules to follow:
- Never snorkel alone. Always have a buddy or someone watching from shore.
- Check conditions before entering. If there’s significant wave action or surge, choose a different spot or a different day.
- Stay out of channels and inlets. The current in the New Harbor inlet can be strong enough to push you where you don’t want to go.
- Respect your limits. The open-ocean sites at Southwest Point are not for casual swimmers. Know your ability.
- Wear high-visibility gear. A brightly colored snorkel vest or surface buoy makes you visible to boats. This matters.
- Sun protection. The back of your neck and legs will burn fast in the water. Apply waterproof sunscreen before you enter.
Getting to Block Island for a Snorkeling Trip
Block Island is accessible by ferry from Point Judith, RI (55 minutes on the high-speed ferry) or from New London, CT (about 2 hours on the Block Island Express). See our complete ferry guide for all options.
You don’t need a car — snorkeling spots are accessible by bike or on foot from Old Harbor. Renting a bike or moped from the harbor is the standard approach.
Frequently Asked Questions
Is the water clear enough for snorkeling at Block Island?
Yes, on calm days with settled conditions. Visibility of 10–20 feet is achievable in summer. After storms or on windy days, visibility drops significantly.
Do I need a wetsuit to snorkel at Block Island?
In July and August, many people snorkel without one, but sessions longer than 30–45 minutes will get uncomfortable. A 3mm shorty or full wetsuit extends your time in the water significantly and is recommended.
Are there any snorkel tours on Block Island?
Dedicated snorkel tours are not a well-established business on Block Island the way they are in tropical destinations. Your best bet is to rent kayaks or paddleboards and paddle to snorkel spots independently, or book a fishing charter that may offer guided water experiences.
Can you see lobster while snorkeling on Block Island?
Yes — American lobster live under rocky ledges throughout Block Island’s shoreline. You’re most likely to spot them at Southwest Point in early morning, tucked under ledges. Don’t disturb or take them — a Rhode Island recreational lobster permit is required to harvest them.
What’s the water temperature like for snorkeling?
Peak summer temperatures reach 68–72°F in July and August. Most people find this manageable for short sessions without a wetsuit; longer sessions or earlier/later in the season calls for a wetsuit.
