Cheapest return flights from Islip to San Juan in May from $300

Best time to book flights for Islip (ISP) to San Juan (SJU) flights at AirHint

AirHint found the following cheapest return flights from Islip (ISP) to San Juan (SJU) in May 2025 (see full year).

Return flights

17 May - 20 May Frontier Airlines
24 May - 31 May Frontier Airlines
19 May - 24 May Frontier Airlines
17 May - 31 May Frontier Airlines
20 May - 29 May Frontier Airlines
16 May - 20 May Frontier Airlines
17 May - 29 May Frontier Airlines
16 May - 18 May Frontier Airlines
17 May - 25 May Frontier Airlines
29 May - 01 Jun Frontier Airlines
23 May - 29 May Frontier Airlines
30 May - 01 Jun Frontier Airlines
29 May - 08 Jun Frontier Airlines
30 May - 02 Jun Frontier Airlines

Also check the deals for one-way flights from Islip to San Juan in May.

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The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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