Last Known Eruption
16d 21h 35m ago

Interval Statistics

Interval Count35
Min33m
Max15y 2d 15h 24m
Mean1y 229d 7h 8m
Median178d 15h 42m

Latest Notes

Note IDStart Time (US/Mountain)End Time (US/Mountain)EntrantNote
37123 23 Sep 2024 @ 0948 --- Graham No evidence of eruptions. Right side boils. No water flowing down the channel between the geyser and the bank.
37076 19 Sep 2024 @ 0949 --- Micah Kipple Vigorous right side boil. Some flow down the side channel. Side vents are dry. No evidence of major activity.
36958 13 Sep 2024 @ 1345 --- Graham No signs of recent eruptions. Grass all standing upright. Vigorous boiling on the right side when the pool is in overflow. Only a trickle of river water in the channel between the bank and the geyser. Platform vents are dry.
36507 22 Aug 2024 @ 1339 --- Craigmon99 Boiling heavily. Cone wet on downstream side. Fresh channel cut into the river.
34864 03 Jun 2024 @ 1230 --- Graham A lot of water in the nearby channel. No boil in ES.
34310 22 Apr 2024 @ 1021 --- DanS Modest edge boils
33822 16 Jan 2024 @ 1252 --- K.Cooper right side no recent eruption
33753 06 Jan 2024 @ 1338 --- Graham Right sidebol. No evidence of any eruption.
29204 29 Oct 2023 @ 1043 --- SantaFe108 Continues to cycle right-side boiling. River is flowing down the side channel.
28865 18 Oct 2023 @ 1529 --- DanS Vigorously boiling at East end of pool splashing above knothole. West boils cycling on and off. River is higher than a couple weeks ago with water flowing in side channel.
28533 29 Sep 2023 @ 0856 --- Graham Still boiling on the right side. There are no signs of eruptions.
28335 18 Sep 2023 @ 1515 --- Micah Kipple Boiling 1-3 feet on north Side. The presence of green upright grass in the splash zone and annual plants growing on the crater rim indicate it has not had any major or even strong minor activity in quite some time.
28150 09 Sep 2023 @ 1617 --- Graham No indication of recent eruptions. The grass is upright, and there's a small plant growing close to the left side minor eruption boil-over spot. Platform vents gurgling when pool is below overflow. Right side boil cycles 13m and 14m. Strongest boils about 2 feet above the rim, slopping water over the right side lip just before the water drops below overflow.
27952 02 Sep 2023 @ 1640 --- SantaFe108 Cycling right-side boiling, from sputtering to bursting, below overflow to overflowing.
26114 07 Jun 2023 @ 0737 --- SantaFe108 Calm and overflowing with a dark colored pool. All side vents off. River is high and side channel is full.
25693 22 May 2023 @ 1406 --- Tara Pool calm and brownish colored, looks like there are cycles with a few bubblew on the left side. The side river channel has a strong flow.
24556 30 Oct 2022 @ 1525 --- SantaFe108 Cycling right side boiling.
24464 20 Oct 2022 @ 1414 21 Oct 2022 @ 1430 DanS Still having strong boils along North rim
24319 08 Oct 2022 @ 1335 08 Oct 2022 @ 1447 DanS Cycling every 3-7 minutes between low vigorous boil along N rim to bursting boils reaching above pool edge platform. Repeats.
24315 08 Oct 2022 @ 1044 --- DanS Heavy boiling along North rim
23629 07 Sep 2022 @ 1734 --- Graham Strong boil on river/right side then water dropped and splashung died down before slowly increasing in activity. Cycle time was 17m. Grass is still all upright, so no indication of any major eruptions recently.
23441 27 Aug 2022 @ 1848 --- SantaFe108 Boiling heavily on the right side, occasionally splashing over the rim
23402 25 Aug 2022 @ 0900 25 Aug 2022 @ 0906 aferrara Noisily boiling, most energetic on right side where splashes are frequently reaching 2', but periodically boiling on left as well. Right boil constant, with 2+ more energetic boiling events every minute.
22131 26 Jun 2022 @ 0924 --- Tara Pool calm and overflowing. Side vents completely quiet, no steam. River is down a bit but the side channel is still full.
21967 13 Jun 2022 @ 1040 --- Graham Platform vents ie. Pool low and calm as river rages by.
21748 05 Jun 2022 @ 1158 --- SantaFe108 Pool is overflowing and calm, side vents to the left are lightly splashing to about about foot. River is flowing through the side channel aswell.
21558 28 May 2022 @ 1545 --- Tara Firehole River is high enough that the side channel is full of brownish water. East Sentinel is flat and calm with steady overflow. The side vents were sloshing lazily to 1-2' for the few minutes I was there.
21365 19 May 2022 @ 1449 --- Graham Pool calm with high water running down the channel by the bank. Small vents on the platform splashing to a foot or 2.
21310 16 May 2022 @ 1118 --- Brando Pool is completely flat. 2 Bison across the river made it interesting.
20804 12 Feb 2022 @ 0925 --- aferrara Full pool rolling boil
20697 15 Jan 2022 @ 0957 --- Graham No evidence of recent eruptions. Grassy area is snow covered and some snow on the platform. Water level low and no boil during brief visit.
20344 13 Nov 2021 @ 0844 --- Mkeller No boiling in overflow.
20214 30 Oct 2021 @ 0928 --- Brando Flat pool with the occasional boil
20163 28 Oct 2021 @ 1722 --- DanS More active than yesterday. Constantly bubbling but no boiling.
20151 27 Oct 2021 @ 1455 27 Oct 2021 @ 1505 DanS No boils, just occasional light bubbling.
20118 25 Oct 2021 @ 0827 --- Darcie No boil. (Or at 8:46)
20067 20 Oct 2021 @ 1635 --- Tara right side boils
20015 17 Oct 2021 @ 1158 --- Darcie Right side boil
19977 14 Oct 2021 @ 1533 --- Tara right side boils
19965 12 Oct 2021 @ 1034 --- aferrara Tall rolling boil, most energetic on the right but whole pool is boiling.
19957 10 Oct 2021 @ 1909 --- Tara Right side boils
19887 05 Oct 2021 @ 0812 --- Darcie Right side boil
19880 04 Oct 2021 @ 0916 --- Darcie Boiling on the right
19865 03 Oct 2021 @ 1128 --- Darcie Right side boil
19799 30 Sep 2021 @ 0740 --- Graham Still right side boils.
19778 29 Sep 2021 @ 0820 --- Graham Still right side boils.
19766 28 Sep 2021 @ 0733 --- Graham Still right side boils.
19755 27 Sep 2021 @ 0656 --- Graham Still right side boils.
19735 26 Sep 2021 @ 0725 --- Graham Still right side boils.
19724 25 Sep 2021 @ 0740 --- Graham Still right side boils.
19689 22 Sep 2021 @ 1720 --- Tara right side boil
19682 22 Sep 2021 @ 0755 --- Graham Still right side boils.
19673 21 Sep 2021 @ 0750 --- Graham Still right side boils.
19667 20 Sep 2021 @ 1604 --- Graham Still right side boils. Weaker activity than last week. Maybe due to higher river level following the rain and snow yesterday.
19654 19 Sep 2021 @ 1525 19 Sep 2021 @ 1535 Mike C slight boiling on right small left side boiling in overflow
19640 18 Sep 2021 @ 0738 --- Graham Still right side boils.
19630 17 Sep 2021 @ 0657 --- Graham Still right side boils.
19627 16 Sep 2021 @ 2014 --- Tara Brief look, right side boiling
19596 16 Sep 2021 @ 0649 --- Graham Still right side boils.
19591 15 Sep 2021 @ 1800 --- Dan A Right side boiling continues
19588 15 Sep 2021 @ 1335 --- Dan A Still right side boiling with cycles every 20 minutes or so
19573 15 Sep 2021 @ 0655 --- Graham Still right side boils..
19572 15 Sep 2021 @ 0030 --- William right side boiling only.
19569 14 Sep 2021 @ 1745 --- CrisG right sided boiling still
19565 14 Sep 2021 @ 1430 --- Dan A North side boiling continues
19554 14 Sep 2021 @ 0725 --- CrisG Right side boilfest continues
19531 13 Sep 2021 @ 1542 --- Suzanne Still boiling on the north side and cycling about every 19 minutes
19523 13 Sep 2021 @ 0909 --- Brian Still in north/right side boil mode
19518 12 Sep 2021 @ 1715 --- Ben VL N. Side boiling, did not stay for an entire cycle.
19511 12 Sep 2021 @ 1447 --- Brian Right side boil-fest continues…
19507 12 Sep 2021 @ 0905 --- William Right side boiling only
19502 12 Sep 2021 @ 0653 --- Graham Still right vent boils.
19492 11 Sep 2021 @ 1950 --- Graham Still right side boil cycles.
19496 11 Sep 2021 @ 1250 --- MarioD Observed from 12:50 to 13:15; several cycles of right side boils noted, some high enough to splash water onto the platform above
19473 11 Sep 2021 @ 0749 --- Graham Still right vent boils.
19451 10 Sep 2021 @ 1840 --- Graham Right vent boils, cycles 17 to 20m reported all day.
19414 10 Sep 2021 @ 0648 --- Graham Still right vent boils.
19395 09 Sep 2021 @ 1745 --- Suzanne Splashing continues from the North vent, cycling every 19 to 20 minutes.
19384 09 Sep 2021 @ 0633 --- Graham Still doing right side boils.
19378 08 Sep 2021 @ 1945 08 Sep 2021 @ 1950 Tara Very brief check, boiling on north/river side, ordinary cycle
19376 08 Sep 2021 @ 1740 --- Dave W All activity still on north side.
19366 08 Sep 2021 @ 0645 --- Graham ES right vent still active. No transition to left yet
19361 07 Sep 2021 @ 1200 07 Sep 2021 @ 1728 geysergaze No change in activity since this morning. 18-21 minutes cycles. All activity on the right / north -west side. Left side not doing much.
19345 07 Sep 2021 @ 0633 --- Graham Right North vent still the active one. Peak 0641, gap, 0801, gap, 0859, gap, 0956, gap, 1152, 1211, 1230,
19337 06 Sep 2021 @ 1800 --- Graham All today's reports have been of N vent cycles 19 or 20m long.
19326 06 Sep 2021 @ 0752 --- Suzanne Boiling from the north side and cycling every 20 minutes. At the peak height water flows into the far left (south) runoff channel and the alcove vent on the north side splashes a few inches above the rim, enough to form puddles on the north side of the crater. The previous peak was at 0751.
19321 05 Sep 2021 @ 1825 --- Graham Observed 3 cycles of 20min with North vent boils. Similar reports all day from other observers.
19317 05 Sep 2021 @ 1515 05 Sep 2021 @ 1635 Tara cycling about every 20 minutes with boiling on north (river) side
19307 04 Sep 2021 @ 2039 --- Graham After normal splashy cycle, pool dropped and went calm. Side vents were steamy and noisy for 7m. Pool stayed calm and did not rise for 10m. 2049 water rose with strong North River side boil this time and then dropped. Side vents steamy and noisy 2056. 2059 water rising. Right side boil, then left joined in and it erupted!
19319 02 Sep 2021 @ 1600 --- Graham 20min cycles of boiling from right North vent, similar to yesterday.
19237 01 Sep 2021 @ 1405 01 Sep 2021 @ 1720 Graham 20min cycles from below overflow to peak water. Vent on River side active, holding thick boil at rim height at peak and splashes 1 foot over rim. Cycles very regular in fill rate and boiling. Similar to what Micah reported on 5 Aug.
19169 30 Aug 2021 @ 2000 --- Dan A 1955 big surging on south side of pool that built into bursting from the center pool around 8’. Water was also bursting from one of the holes
19163 30 Aug 2021 @ 1202 30 Aug 2021 @ 1445 Tara I suspect a major eruption has occurred recently, grass is matted on the SSE side, water is slightly murky. Minor activity has changed drastically from 1 week ago, when I saw only moderate overflow and weak 6-18" cyclical boiling on the north (river) side. Today I arrived to find heavy overflow and boiling to 1-3' on the south (bank) side. At 1204 his built to surging to 3-5', followed by churning bursts from the center of the pool reaching 4-8' for about a minute, with overflow spilling over all sides. At 1206 the water level began to drop and the surging subsided. As the water fell to its lowest point 1.5' below the bathtub mark, the side vent to the south began to gurgle and then splash weakly to 1-3' for about a minute. Boiling and bursting continued on the south side from a low water level reaching 1-3' but becoming weaker as the water level rose. 1217 the pool reached overflow again. 1218 variable boiling resumed on south side, highest water level 2" below bathtub mark, 1220 water level drop to 6-8" below mark. 1227 water had risen to 2-3" below mark, pool mostly calm with some light boiling, still holding at 1235. 1240 water level 2" below mark, increasing boiling on south side. 1252 water level rose to bathtub mark, heavier overflow, boiling 1-3' on south side. 1254 boiling extending into center of pool. 1255 water level dropped slightly and bursting began that built to churning at 1256. Action similar to previous minor but weaker, max height 4-5' and d~1m. Side vent gurgling after but only a few.drops of water seen. 1257 water level drop to about 1' below mark. 1306 water level back up to mark, boiling extending frol south side into center of pool. Side vent stopped gurgling at this time. 1307 bursting and churning d~1m h~4-6', 1309 water level drop & side vent gurgling with spits 1-3', more bursting briefly at 1310. 1315 water level holding 8" below mark, side vent continues to gurgle. Cycles continued to stabilize at about 20 minutes, with peak boiling reaching ~4' occurring as the pool dropped.
19136 28 Aug 2021 @ 1918 --- User34 Overflowing and boiling vigorously from the righthand side
18842 05 Aug 2021 @ 1407 05 Aug 2021 @ 1503 Micah Kipple East Sentinel is cycling it's water level up and down approximately every 20 minutes (first ovf to first ovf). Upon reaching overflow, superheated boiling 3-12" high commences on the North (River side) of the crater. This waxes and wanes until about 10 minutes after first overflow, when the entire pool suddenly lifts ~3" and the superheated boiling surges to 2', sending runoff trickling down the backside into the river. When the pool drops about 15 minutes after first overflow, there is some small lazy bursting from a single vent on the south (Bank) side of the pool to about 12". Then the water starts coming up and the cycle repeats.
18803 02 Aug 2021 @ 0945 --- hkoenig Appears to have had major eruption in last couple of days. Some catch basins full. Dead grasses pointing upriver and dead plants as much as 10m from the vent in southern alcove. Flow marks still visible at spots. 25cm high boiling along downstream rim. Based on Tara Cross' comment, added an eruption entry for ~2021 Aug 01 01:00
12400 07 Jul 2019 @ 1152 --- User34 Flat, river flowing well through near channel.
9929 29 Aug 2018 @ 1720 --- Micah Kipple Still flat and being drowned by the river.
9204 15 Jul 2018 @ 1850 --- Micah Kipple Pool surface quiet but steadily overflowing and almost imperceptibly rising and falling. Side vent is completely inundated by the side channel of the Firehole.
5217 22 Aug 2017 @ 1041 --- CrisG pool full and quiet. no bubbling or splashing.
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