Question: John Cabot had a first landing site of the province that blocks the mouth of what river?

Context paragraphs:
Maryland Day: Maryland Day is a legal holiday in the U.S. state of Maryland.  It is observed on the anniversary of the March 25, 1634, landing of the first European settlers in the Province of Maryland, the third English colony to be settled in British North America.  On this day settlers from ""The Ark"" and the smaller ""The Dove"" first stepped foot onto Maryland soil, at St. Clement's Island in the Potomac River.  The settlers were about 150 in number, departed from Gravesend on the Thames River downstream from London.  Three Jesuit priests were collected from Cowes on the Isle of Wight in England where they avoided having to give the oath of allegiance and supremacy to the King.  The colony's grant was renewed to Cecil Calvert, 2nd Baron Baltimore, (1605-1675), two years prior by Charles I of England, after first being given to his father Sir George Calvert, 1st Baron Baltimore, (1574-1632), along with the title of "Lord Baltimore", and a first grant in Acadia, in Newfoundland, (modern Canada), (title named after lands and town Baltimore, in Ireland) who had served the King in many official and personal capacities as Secretary of State, 1619-1625 (despite his conversion to Roman Catholicism).  In thanksgiving for the safe landing, Jesuit Father Andrew White celebrated the Mass for the colonists led by the younger brother of Lord Baltimore, Leonard Calvert, (1606-1647), who served as the first governor, and perhaps for the first time ever in this part of the world on the first landing at Blackistone Island, later known as St. Clement's Island off the northern shore of the Potomac River, which was the new border between the new colony and the earlier English settlements in Virginia) and erected a large cross.  The landing coincided with the Feast of the Annunciation, a holy day honoring Mary, and the start of the new year in England's legal calendar (prior to 1752).  Maryland Day on 25 March celebrates the 1634 landing at St Clements.  Later the colonists and their two ships sailed further back down river to the southeast to settle a capital at St. Mary's City near the point where the Potomac flows into the Chesapeake Bay.

Newfoundland (island): Newfoundland ( ; French: "Terre-Neuve" ) is a large Canadian island off the east coast of the North American mainland, and the most populous part of the Canadian province of Newfoundland and Labrador.  It has 29 percent of the province's land area.  The island is separated from the Labrador Peninsula by the Strait of Belle Isle and from Cape Breton Island by the Cabot Strait.  It blocks the mouth of the Saint Lawrence River, creating the Gulf of Saint Lawrence, the world's largest estuary.  Newfoundland's nearest neighbour is the French overseas community of Saint-Pierre and Miquelon.

William Penn Landing Site: The monument at the William Penn Landing Site marks the spot of the first landing of William Penn on the territory of Pennsylvania, on October 28 or 29, 1682 (O.S.).  Penn, the founder of the Province of Pennsylvania, landed in the only town in the province, then known as Upland, but since known as Chester.

Cook Landing Site: The Cook Landing Site in Waimea on Kauaʻ i island in Hawaii, is where Captain James Cook landed at the mouth of the Waimea River on January 20, 1778.  Cook was the first European reported to have sighted the Hawaiian Islands, and the January 20 landfall on southwestern Kauaʻ i was his first arrival upon Hawaiian soil.  Cook Landing Site was registered as a National Historic Landmark on December 29, 1962.  Hofgaard Park is a small county park in Waimea, a few blocks from the actual landing, that commemorates the historic events of Cook's landing.

Plymouth, Mississippi: Plymouth was an early settlement in Mississippi in present-day Lowndes County.  Plymouth was located at on the west bank of the Tombigbee River.  It was formed around 1819, nucleating at the fortified house of John Pitchlynn, the U.S. interpreter for the Choctaw Agency for communications with the Choctaw Nation.  The low-lying landing site of the village was prone to repeated flooding.  While both Plymouth and its sister town of Columbus across the river had high bluffs, Plymouth's landing site did not have easy access to the bluff heights.  By the 1840s, the village site was abandoned, with most of the residents moving across the river.

John Cabot Academy: John Cabot Academy formerly John Cabot CTC, is one of 15 City Technology Colleges that first opened for students in the 1993/1994 academic year.  It has since converted to Academy status on 1 September 2007.  It is located east of Bristol, England in the Kingswood area of South Gloucestershire and is named after John Cabot, an explorer who set out from Bristol and reached the Americas in 1497.  The academy has 1,068 students, about 220 of whom are in the sixth form.

Eberswalde (crater): Eberswalde, formerly known as Holden NE, is a partially buried impact crater in Margaritifer Terra, Mars.  Eberswalde Crater lies just to the north of Holden Crater, a large crater that may have been a lake.  The 65.3-km-diameter crater, centered at 24°S, 33°W, is named after the German town of the same name, in accordance with the International Astronomical Union's rules for planetary nomenclature.  It was one of the final four proposed landing sites for the Mars rover Mars Science Laboratory mission.  This extraterrestrial geological feature lies situated within the Margaritifer Sinus quadrangle (MC-19) region of Mars.  Although not chosen, it was considered a potential landing site for the "Mars 2020" rover, and in the second Mars 2020 Landing Site Workshop it survived the cut and was among the top eight sites still in the running.

John Cabot: John Cabot (Italian: "Giovanni Caboto" , Venetian: "Zuan Chabotto" ; c. 1450 – c. 1500) was a Venetian navigator and explorer whose 1497 discovery of the coast of North America under the commission of Henry VII of England was the first European exploration of the mainland of North America since the Norse visits to Vinland in the eleventh century.  To mark the celebration of the 500th anniversary of Cabot's expedition, both the Canadian and British governments elected Cape Bonavista, Newfoundland, as Cabot's first landing site.  However, alternative locations have also been proposed.

Bradbury Landing: Bradbury Landing is a landing location on the planet Mars inside Gale crater.  It marks the landing site of Mars Science Laboratory "Curiosity" rover on August 6, 2012.  The location was named by NASA for Ray Bradbury on August 22, 2012, his 92nd birthday, in honor of the author who died a few months earlier, on June 5.  The coordinates of the landing site are: .

Tuscumbia Landing Site: The Tuscumbia Landing Site is a historic port site near Sheffield, Alabama.  The landing was established in 1824 at the mouth of Spring Creek on the Tennessee River.  As large craft could not navigate Spring Creek to reach Tuscumbia, the landing was built to transfer goods to and from the town.  The New Orleans and Tuscumbia Steamboat Company was created in 1825, and connected The Shoals with towns on the Mississippi and Ohio Rivers.  Wagons were used to haul goods between the landing and the town until a horse-drawn railroad, the first railroad west of the Appalachian Mountains, was built from 1831 to 1832.  The line was later extended to Decatur in 1834, bypassing the treacherous shoals on the Tennessee River, and was renamed the Tuscumbia, Courtland and Decatur Railroad.  The landing was also a stop for many Muscogee and Cherokee along the Trail of Tears.

Supporting paragraphs: John Cabot Newfoundland (island)
Answer: Saint Lawrence